#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
// input and output of modint
istream &operator>>(istream &is, modint998244353 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint998244353 &a) { return os << a.val(); }
istream &operator>>(istream &is, modint1000000007 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint1000000007 &a) { return os << a.val(); }
template<int m> istream &operator>>(istream &is, static_modint<m> &a) { long long v; is >> v; a = v; return is; }
template<int m> ostream &operator<<(ostream &os, const static_modint<m> &a) { return os << a.val(); }
template<int m> istream &operator>>(istream &is, dynamic_modint<m> &a) { long long v; is >> v; a = v; return is; }
template<int m> ostream &operator<<(ostream &os, const dynamic_modint<m> &a) { return os << a.val(); }
#define rep_(i, a_, b_, a, b, ...) for (int i = (a), lim##i = (b); i < lim##i; ++i)
#define rep(i, ...) rep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
#define drep_(i, a_, b_, a, b, ...) for (int i = (a)-1, lim##i = (b); i >= lim##i; --i)
#define drep(i, ...) drep_(i, __VA_ARGS__, __VA_ARGS__, __VA_ARGS__, 0)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#ifdef LOCAL
void debug_out() { cerr << endl; }
template <class Head, class... Tail> void debug_out(Head H, Tail... T) { cerr << ' ' << H; debug_out(T...); }
#define debug(...) cerr << 'L' << __LINE__ << " [" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define dump(x) cerr << 'L' << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
template<class T> using V = vector<T>;
template<class T> using VV = V<V<T>>;
using ll = long long;
using ld = long double;
using Vi = V<int>;  using VVi = VV<int>;
using Vl = V<ll>;   using VVl = VV<ll>;
using Vd = V<ld>;   using VVd = VV<ld>;
using Vb = V<bool>; using VVb = VV<bool>;
template<class T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
template<class T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<class... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<class T> inline int sz(const T &x) { return x.size(); }
template<class T> inline bool chmin(T &a, const T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T &a, const T b) { if (a < b) { a = b; return true; } return false; }
template<class T1, class T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }
template<class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { os << '(' << p.first << ", " << p.second << ')'; return os; }
template<class T, size_t n> istream &operator>>(istream &is, array<T, n> &v) { for (auto &e : v) is >> e; return is; }
template<class T, size_t n> ostream &operator<<(ostream &os, const  array<T, n> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> istream &operator>>(istream &is, vector<T> &v) { for (auto &e : v) is >> e; return is; }
template<class T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> istream &operator>>(istream &is, deque<T> &v) { for (auto &e : v) is >> e; return is; }
template<class T> ostream &operator<<(ostream &os, const deque<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> inline void deduplicate(vector<T> &a) { sort(all(a)); a.erase(unique(all(a)), a.end()); }
template<class T> inline int count_between(const vector<T> &a, T l, T r) { return lower_bound(all(a), r) - lower_bound(all(a), l); } // [l, r)
inline ll ceil_div(const ll x, const ll y) { return (x+y-1) / y; } // ceil(x/y)
inline int floor_log2(const ll x) { assert(x > 0); return 63 - __builtin_clzll(x); } // floor(log2(x))
inline int ceil_log2(const ll x) { assert(x > 0); return (x == 1) ? 0 : 64 - __builtin_clzll(x-1); } // ceil(log2(x))
inline int popcount(const ll x) { return __builtin_popcountll(x); }
inline void fail() { cout << -1 << '\n'; exit(0); }
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
// constexpr int INF = numeric_limits<int>::max() >> 1;
// constexpr ll INFll = numeric_limits<ll>::max() >> 1;
// constexpr ld EPS = 1e-10;
// const ld PI = acos(-1.0);
using mint = modint998244353;
// using mint = modint1000000007;
// using mint = modint;
// using Vm = V<mint>; using VVm = V<Vm>;


// O(m + log mod)
// only for mod > m
template<class T> struct factorial {
private:
  int MAX;
  vector<T> _fac, _invf;
  // vector<T> _dfac;
public:
  factorial(int m = -1) {
    if (m < 0) return;
    MAX = m; _fac.assign(m+1, 1); _invf.assign(m+1, 1);
    rep(i, 2, m+1) _fac[i] = _fac[i-1] * i;
    _invf[m] /= _fac[m];
    drep(i, m+1, 3) _invf[i-1] = _invf[i] * i;
    // _dfac.assign(m+1, 1);
    // rep(i, 2, m) _dfac[i] = _dfac[i-2] * i;
  }
  T fac(int n) const { return _fac[n]; }
  T inv_fac(int n) const { return _invf[n]; }
  // T double_fac(int n) const { return _dfac[n]; }
  T binom(int n, int k) const {
    if (k < 0 || n < k) return 0;
    assert(n <= MAX);
    return _fac[n] * _invf[k] * _invf[n-k];
  }
  T perm(int n, int k) const {
    if (k < 0 || n < k) return 0;
    assert(n <= MAX);
    return _fac[n] * _invf[n-k];
  }
  // 重複組合せ (n 個の元から重複を許して k 個選ぶ方法の数) は binom(n+k-1, k)
};


mint solve() {
  int n, k; cin >> n >> k;
  factorial<mint> fc(k);
  Vi a(n); cin >> a;
  int S = accumulate(all(a), 0);

  priority_queue<pair<ld, int>> pq;
  rep(i, n) pq.emplace(ld(a[i]) / S, i);

  Vi x(n);
  rep(_, k) {
    auto [z, i] = pq.top(); pq.pop();
    x[i]++;
    pq.emplace(ld(a[i]) / S / (x[i]+1), i);
  }

  mint ans = fc.fac(k) / mint(S).pow(k);
  rep(i, n) {
    ans *= mint(a[i]).pow(x[i]);
    ans *= fc.inv_fac(x[i]);
  }
  return ans;
}


int main() {
  // solve();
  int t; cin >> t;
  rep(i, t) cout << solve() << '\n';
}