#include <bits/stdc++.h>
#pragma GCC optimize("-O2")
using namespace std;
const int N = 2e5 + 5, MOD = 1e9 + 7;
const long double EPS = 1e-9;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int i, n;
    cin >> n;
    vector<int> a(n), ans;
    for (int i = 0; i < n; ++i) cin >> a[i];
    int e = 0, o = 0;
    for (i = 0; i < n; i++) {
      if (a[i] % 2 == 0)
        e++;
      else
        o++;
    }
    if (o < 2 and e == 0)
      cout << "-1\n";
    else {
      if (e) {
        for (i = 0; i < n; i++)
          if (a[i] % 2 == 0) ans.push_back(i + 1);
      } else {
        for (i = 0; i < n; i++) {
          ans.push_back(i + 1);
          if (ans.size() % 2 == 0) break;
        }
      }
      cout << ans.size();
      cout << '\n';
      for (auto i : ans) cout << i << " ";
      cout << '\n';
    }
  }
  return 0;
}
