#include <bits/stdc++.h>
using namespace std;
int main() {
  int q;
  cin >> q;
  for (int i = 0; i < q; i++) {
    int n, r;
    cin >> n >> r;
    int arr[n];
    for (int j = 0; j < n; j++) {
      cin >> arr[j];
    }
    sort(arr, arr + n);
    int shots = 0, act[n], p = 0;
    act[0] = arr[0];
    p++;
    for (int j = 1; j < n; j++) {
      if (arr[j] == arr[j - 1]) {
      } else {
        act[p] = arr[j];
        p++;
      }
    }
    for (int j = 0; j < p; j++) {
      if (act[p - j - 1] - j * r <= 0) {
        break;
      }
      shots++;
    }
    cout << shots << endl;
  }
  return 0;
}
