#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint998244353;

constexpr int FACT_SIZE = 1000000;
mint Fact[FACT_SIZE + 1];
mint iFact[FACT_SIZE + 1];
mint inv[FACT_SIZE + 1];
const auto fact_init = [] {
    Fact[0] = mint::raw(1);
    for(int i = 1; i <= FACT_SIZE; ++i) {
        Fact[i] = Fact[i-1] * i;
    }
    iFact[FACT_SIZE] = Fact[FACT_SIZE].inv();
    for(int i = FACT_SIZE; i; --i) {
        iFact[i-1] = iFact[i] * i;
        inv[i] = iFact[i] * Fact[i-1];
    }
    return false;
}();

mint comb(int n, int k) {
    if (k == 0) return mint::raw(1);
    assert(n >= 0 && k >= 0);
    if (k > n) return mint::raw(0);
    return Fact[n] * iFact[n - k] * iFact[k];
}

mint icomb(int n, int k) {
    return iFact[n] * Fact[n - k] * Fact[k];
}

mint fact(int n) {return Fact[n];}
mint perm(int n, int k) {
    assert(0 <= n);
    return Fact[n] * iFact[n - k];
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while (tt--) {
    int n, l;
    cin >> n >> l;
    VI d(n);
    rep(i, n) cin >> d[i], d[i] *= 2;
    int a = 0;
    int ptr = 0;
    rep(i, n) {
      if (d[i] >= l) break;
      while (ptr < n && d[ptr] < d[i] + l) ptr++;
      a += ptr < n && d[ptr] == d[i] + l;
    }
    if (a <= 1) {
      mint ans;
      rep(i, n) ans += n * inv[n-i];
      cout << ans.val() << '\n';
      continue;
    }
    int b = n - 2 * a;
    // (1+2x)^a (1+x)^b
    vector<mint> f1(a + 1), f2(b + 1);
    mint p2 = 1;
    rep(i, a + 1) {
      f1[i] = comb(a, i) * p2;
      p2 *= 2;
    }
    rep(i, b + 1) f2[i] = comb(b, i);
    auto f = convolution(f1, f2);
    int sz = f.size();
    mint ans;
    rep(i, sz) {
      ans += f[i] * Fact[i] * Fact[n-i] * iFact[n] * n * inv[n-i];
    }
    // (1+2x)^(a-1) (1+x)^b
    rep(i, sz - 1) f[i+1] -= 2 * f[i];
    rep(i, sz - 1) if (f[i].val()) {
      ans += a * f[i] * Fact[i+2] * Fact[n-i-2] * iFact[n] * n * inv[n-i-2];
    }
    cout << ans.val() << '\n';
  }
}