from fractions import Fraction
import heapq
import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)
mod = 998244353
U = 10 ** 5 + 10

fact = [1] * (U+1)
inv = [1] * (U+1)
for i in range(1, U+1):
    fact[i] = fact[i-1] * i % mod
inv[U] = pow(fact[i], mod-2, mod)
for i in reversed(range(U)):
    inv[i] = inv[i+1] * (i + 1) % mod


T = int(input())
for _ in range(T):
    N, K = map(int, input().split())
    A = list(map(int, input().split()))
    S = sum(A) % mod
    S_inv = pow(S, mod-2, mod)

    que = [(-Fraction(a), i) for i, a in enumerate(A)]
    heapq.heapify(que)
    cnt = [0] * N
    for _ in range(K):
        f, idx = heapq.heappop(que)
        f = -f
        num, div = f.as_integer_ratio()
        cnt[idx] += 1
        heapq.heappush(que, (-Fraction(num, div + 1), idx))

    res = fact[K]
    for i in range(N):
        res = res * pow(A[i] * S_inv, cnt[i], mod)
        res = res * inv[cnt[i]] % mod
    print(res)