#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, e = 0, o = 0, f = 1;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      if (a[i] % 2 == 0)
        e++;
      else
        o++;
      if ((e || o % 2 == 0) && f == 1) {
        f = 0;
        if (e) {
          cout << 1 << endl << i + 1;
        } else {
          cout << o << endl;
          for (int j = 0; j < i + 1; j++) {
            if (a[j] % 2 == 1) cout << j + 1 << " ";
          }
        }
      }
    }
    if (f == 1) cout << -1;
    cout << endl;
  }
}
