#include <stdio.h>

const int Mod = 998244353;
long long fact[100001], fact_inv[100001];

typedef struct {
	long double key;
	int id;
} data;

void merge_sort(data x[], int n)
{
	static data y[100001] = {};
	if (n <= 1) return;
	merge_sort(&(x[0]), n/2);
	merge_sort(&(x[n/2]), (n+1)/2);
	
	int i, p, q;
	for (i = 0, p = 0, q = n/2; i < n; i++) {
		if (p >= n/2) y[i] = x[q++];
		else if (q >= n) y[i] = x[p++];
		else y[i] = (x[p].key < x[q].key)? x[p++]: x[q++];
	}
	for (i = 0; i < n; i++) x[i] = y[i];
}

long long div_mod(long long x, long long y, long long z)
{
	if (x % y == 0) return x / y;
	else return (div_mod((1 + x / y) * y - x, (z % y), y) * z + x) / y;
}

long long pow_mod(int n, int k)
{
	long long N, ans = 1;
	for (N = n; k > 0; k >>= 1, N = N * N % Mod) if (k & 1) ans = ans * N % Mod;
	return ans;
}

long long combination(int n, int k)
{
	return fact[n] * fact_inv[k] % Mod * fact_inv[n-k] % Mod;
}

void solve()
{
	int i, k = 0, N, K, sum = 0;
	long long ans = 1;
	static int A[100001], num[100001];
	static long long prob[100001];
	static data d[100001];
	scanf("%d %d", &N, &K);
	for (i = 0; i < N; i++) {
		scanf("%d", &(A[i]));
		sum += A[i];
	}
	for (i = 0; i < N; i++) {
		prob[i] = div_mod(A[i], sum, Mod);
		num[i] = (long long)A[i] * K / sum;
		k += num[i];
		d[i].key = (long double)A[i] * K / sum - num[i];
		d[i].id = i;
	}
	merge_sort(d, N);
	for (i = 1; i <= K - k; i++) num[d[N-i].id]++;
	for (i = 0; i < N; i++) {
		ans = ans * pow_mod(prob[i], num[i]) % Mod * combination(K, num[i]) % Mod;
		K -= num[i];
	}
	printf("%lld\n", ans);
}

int main()
{
	int i;
	for (i = 1, fact[0] = 1; i <= 100000; i++) fact[i] = fact[i-1] * i % Mod;
	for (i = 99999, fact_inv[100000] = div_mod(1, fact[100000], Mod); i >= 0; i--) fact_inv[i] = fact_inv[i+1] * (i + 1) % Mod;

	int t, T;
	scanf("%d", &T);
	for (i = 1; i <= T; i++) solve();
	fflush(stdout);
	return 0;
}