#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename A, typename B>
istream& operator>>(istream& input, pair<A, B>& x) {
  input >> x.first >> x.second;
  return input;
}
template <typename A>
istream& operator>>(istream& input, vector<A>& x) {
  for (auto& i : x) input >> i;
  return input;
}
template <typename A>
ostream& operator<<(ostream& output, vector<A>& x) {
  for (auto& i : x) output << i << ' ';
  return output;
}
void add(long long&, long long);
long long sub(long long, long long);
long long mul(long long, long long);
long long powz(long long, long long);
long long fact_pow(long long n, long long k) {
  long long res = 0;
  while (n) {
    n /= k;
    res += n;
  }
  return res;
}
long long expos(long long a, long long b) {
  long long m = mod - 1;
  return ((a)*1ll * (b)) % m;
}
bool sortinrev(const pair<long long, long long>& a,
               const pair<long long, long long>& b) {
  return (a.first > b.first);
}
long long binpow(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a;
    a = a * 1llu * a;
    b >>= 1;
  }
  return res;
}
const long long N = 1e6 + 1;
void solve() {
  long long n;
  cin >> n;
  vector<long long> v(n);
  cin >> v;
  sort(v.begin(), v.end(), greater<long long>());
  long long cnt = 1;
  for (long long i = 0; i < n; i++) {
    if (v[i] >= cnt)
      cnt++;
    else {
      cnt--;
      break;
    }
  }
  if (cnt > n) {
    cout << n;
  } else {
    cout << cnt;
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long tc = 1;
  cin >> tc;
  for (long long _ = 0; _ < tc; _++) {
    solve();
    if (_ != tc - 1) cout << "\n";
  }
}
long long powz(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1) res = mul(res, a);
    b /= 2;
    a = mul(a, a);
  }
  return res;
}
long long sub(long long a, long long b) {
  a -= b;
  if (a < 0) {
    a += mod;
  }
  return a;
}
long long mul(long long a, long long b) { return ((a)*1ll * (b)) % mod; }
void add(long long& a, long long b) {
  a += b;
  if (a >= mod) a -= mod;
}
