#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
#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()
template<class T> using V = vector<T>;
using ld = long double;
using Vi = V<int>;
using mint = modint998244353;


// O(m + log mod)
// only for mod > m
template<class T> struct factorial {
private:
  int MAX;
  vector<T> _fac, _invf;
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;
  }
  T fac(int n) const { return _fac[n]; }
  T inv_fac(int n) const { return _invf[n]; }
};


int solve() {
  int n, k; cin >> n >> k;
  factorial<mint> fc(k);
  Vi a(n); for (auto &e : a) cin >> e;
  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.val();
}


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