#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cctype>

#include <algorithm>
#include <random>
#include <bitset>
#include <queue>
#include <functional>
#include <set>
#include <map>
#include <vector>
#include <chrono>
#include <iostream>
#include <limits>
#include <numeric>

#define LOG(FMT...) fprintf(stderr, FMT)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<class T>
istream &operator>>(istream &is, vector<T> &v) {
  for (T &x : v)
    is >> x;
  return is;
}

template<class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  if (!v.empty()) {
    os << v.front();
    for (int i = 1; i < v.size(); ++i)
      os << ' ' << v[i];
  }
  return os;
}

const int P = 1000000007;

int norm(int x) { return x >= P ? (x - P) : x; }

void add(int &x, int y) { if ((x += y) >= P) x -= P; }

void sub(int &x, int y) { if ((x -= y) < 0) x += P; }

void exGcd(int a, int b, int &x, int &y) {
  if (!b) {
    x = 1;
    y = 0;
    return;
  }
  exGcd(b, a % b, y, x);
  y -= a / b * x;
}

int inv(int a) {
  int x, y;
  exGcd(a, P, x, y);
  return norm(x + P);
}

const int N = 100010;

int nv[N];

int main() {
#ifdef ELEGIA
  freopen("test.in", "r", stdin);
  int nol_cl = clock();
#endif
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  for (int i = 1; i < N; ++i) nv[i] = inv(i);

  int T;
  cin >> T;
  while (T--) {
    int n, m;
    cin >> n >> m;
    --m;
    vector<vector<int>> g(n);
    for (int rep = 1; rep < n; ++rep) {
      int u, v;
      cin >> u >> v;
      --u;
      --v;
      g[u].push_back(v);
      g[v].push_back(u);
    }
    vector<int> prt(n), vis(n);
    function<void(int)> dfs = [&](int u) {
      vis[u] = 1;
      for (int v : g[u])
        if (!vis[v]) {
          prt[v] = u;
          dfs(v);
        }
    };
    prt[0] = -1;
    dfs(0);
    int p0 = 1, p1 = 0;
    while (m) {
      m = prt[m];
      int ch = g[m].size();
      if (m) --ch;
      p1 = (p1 + p0 * (ll)(ch - 1) % P * nv[g[m].size() - 1]) % P * nv[g[m].size()] % P;
      p0 = p0 * (ll)nv[g[m].size()] % P;
    }
    cout << norm(p0 + p1) << '\n';
  }

#ifdef ELEGIA
  LOG("Time: %dms\n", int ((clock()
          -nol_cl) / (double)CLOCKS_PER_SEC * 1000));
#endif
  return 0;
}