#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18;
const long long mod = 1e9 + 7;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long q;
  cin >> q;
  ;
  for (long long i = (1); i <= (q); i++) {
    long long n;
    cin >> n;
    ;
    long long r;
    cin >> r;
    ;
    set<long long, greater<long long>> s;
    for (long long i = (1); i <= (n); i++) {
      long long x;
      cin >> x;
      ;
      s.insert(x);
    }
    long long k = 0, st = 0;
    for (long long j : s) {
      if (j - r * k <= 0) {
        cout << k << '\n';
        st = 1;
        break;
      }
      k++;
    }
    if (!st) cout << k << '\n';
  }
}
