/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.06.20 23:10:04
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

template< int MOD >
struct mint {
public:
    long long x;
    mint(long long x = 0) :x((x%MOD+MOD)%MOD) {}
    mint(std::string &s) {
        long long z = 0;
        for (int i = 0; i < s.size(); i++) {
            z *= 10;
            z += s[i] - '0';
            z %= MOD;
        }
        this->x = z;
    }
    mint& operator+=(const mint &a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator-=(const mint &a) {
        if ((x += MOD - a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator*=(const mint &a) {
        (x *= a.x) %= MOD;
        return *this;
    }
    mint& operator/=(const mint &a) {
        long long n = MOD - 2;
        mint u = 1, b = a;
        while (n > 0) {
            if (n & 1) {
                u *= b;
            }
            b *= b;
            n >>= 1;
        }
        return *this *= u;
    }
    mint operator+(const mint &a) const {
        mint res(*this);
        return res += a;
    }
    mint operator-() const {return mint() -= *this; }
    mint operator-(const mint &a) const {
        mint res(*this);
        return res -= a;
    }
    mint operator*(const mint &a) const {
        mint res(*this);
        return res *= a;
    }
    mint operator/(const mint &a) const {
        mint res(*this);
        return res /= a;
    }
    friend std::ostream& operator<<(std::ostream &os, const mint &n) {
        return os << n.x;
    }
    friend std::istream &operator>>(std::istream &is, mint &n) {
        long long x;
        is >> x;
        n = mint(x);
        return is;
    }
    bool operator==(const mint &a) const {
        return this->x == a.x;
    }
    bool operator!=(const mint &a) const {
        return this->x != a.x;
    }
    mint pow(long long k) const {
        mint ret = 1;
        mint p = this->x;
        while (k > 0) {
            if (k & 1) {
                ret *= p;
            }
            p *= p;
            k >>= 1;
        }
        return ret;
    }
};
constexpr int MOD = 998244353;
int main() {
    int t;cin >> t;
    using T = pair<int,int>;
    while(t--) {
        int n,k;cin >> n >> k;
        vector<int> a(n);
        mint<MOD> ans = 1;
        for (int i = 2; i <= k; i++) ans *= i;
        int sum = 0;
        for (int i = 0; i < n; i++) {
            cin >> a[i];
            sum += a[i];
        }
        priority_queue<T,vector<T>,function<bool(T,T)>> pq([&](T x,T y){return a[x.first]*y.second < a[y.first]*x.second;});
        for (int i = 0; i < n; i++) pq.push({i,1});
        while(k--) {
            auto p = pq.top(); pq.pop();
            pq.push({p.first,p.second+1});
            ans *= mint<MOD>(a[p.first])/sum/p.second;
        }
        cout << ans << endl;
    }
    return 0;
}