from collections import defaultdict 
mod = 998244353
lim = 10 ** 6

f = [1] * lim
invf = [1] * lim
inv = [1] * lim
p2 = [1] * lim
p2[1] = 2
for i in range(2, lim):
    f[i] = f[i-1] * i % mod
    inv[i] = -inv[mod%i] * (mod//i) % mod
    invf[i] = invf[i-1] * inv[i] % mod
    p2[i] = p2[i-1] * 2 % mod

def comb(n, r):
    return f[n] * invf[n-r] % mod * invf[r] % mod

def solve():
    n, l = [int(x) for x in input().split()]
    d = [int(x) for x in input().split()]
    
    # 直径をなすペアの個数
    pair = 0
    if l % 2 == 0:
        cnt = defaultdict(int)
        for x in d:
            cnt[x%(l//2)] += 1
        for c in cnt.values():
            if c == 2:
                pair += 1
    
    ans = 0
    if pair <= 1:
        for i in range(1, n + 1):
            ans += n * inv[i] % mod
        print(ans % mod)
        return 
        
    one = n - pair * 2
    ans += n * inv[2*pair] % mod
    for c in range(1, pair + 3):
        q = n * inv[2*pair-c] % mod
        t = 0
        if 1 <= c <= pair:
            t += comb(pair, c) * p2[c] % mod
        if 2 <= c <= pair + 1:
            t += pair * comb(pair-1, c-2) * p2[c-2] % mod
        t = t * pow(comb(2*pair, c), -1, mod) % mod
        ans += t * q % mod
    
    print(ans % mod)

t = int(input())
for i in range(t):
    solve()