from bisect import bisect_left

mod = 998244353

def solve():
    N, L = map(int, input().split())
    D = set(map(int, input().split()))

    C = 0
    if L%2 == 0:
        for d in D:
            op = d + L//2
            if op in D:
                C += 1
    if C <= 1:
        ans = 0
        for i in range(1, N+1):
            ans += N * pow(i, -1, mod)
            ans %= mod
        print(ans)
        return

    dp = [[0 for j in range(C+1)] for i in range(3)]

    for i in range(2, -1, -1):
        for j in range(C, -1, -1):
            if i > j: continue
            if i == 2:
                dp[i][j] = 0
                continue
            dp[i][j] = 1
            if j < C:
                dp[i][j] += 2 * (C - j) * pow(N, -1, mod) % mod * dp[i][j+1]
                dp[i][j] %= mod
            if i < j:
                dp[i][j] += (j - i) * pow(N, -1, mod) % mod * dp[i+1][j]
                dp[i][j] %= mod
            dp[i][j] *= N * pow(2 * C - i - j, -1, mod) % mod
            dp[i][j] %= mod
    
    print(dp[0][0])

for _ in range(int(input())):
    solve()