#include <bits/stdc++.h>
using namespace std;
#include <atcoder/modint>
using mint = atcoder::modint998244353;

void solve() {
    int N, L; cin >> N >> L;
    vector<int> D(N);
    for (int& d : D) cin >> d;

    int C = 0;
    if (L%2 == 0) {
        for (int d : D) {
            int op = d + L/2;
            if (binary_search(D.begin(), D.end(), op)) C++;
        }
    }

    if (C <= 1) {
        //最後まで
        mint ans = 0;
        for (int i = 1; i <= N; i++) ans += mint(N) / i;
        cout << ans.val() << endl;
        return;
    }

    vector dp(3, vector<mint>(C+1, 0));
    for (int i = 2; i >= 0; i--) {
        for (int j = C; j >= 0; j--) {
            if (i > j) continue;
            if (i == 2) {
                dp[i][j] = 0;
                continue;
            }
            dp[i][j] = 1;
            if (j < C) dp[i][j] += mint(2 * (C - j)) / N * dp[i][j+1];
            if (i < j) dp[i][j] += mint(j - i) / N * dp[i+1][j];
            dp[i][j] *= mint(N) / (2 * C - i - j);
        }
    }

    cout << dp[0][0].val() << endl;
}

int main() {
    int T; cin >> T;
    while(T--) solve();
}