#include <iostream>
#include <cstring>
#include <utility>
#include <vector>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <map>
#include <cmath>
#include <complex>
#include <array>
#include <ctime>
#include <cassert>
#include <set>
#include <iomanip>
#include <random>
#include <cstdlib>
#include <chrono>
#include <bitset>

using namespace std;
const int mod = 1000000007;
int inv[100005];
int add(int a, int b) {
    a += b;
    if (a >= mod) a -= mod;
    if (a < 0) a += mod;
    return a;
}

int mul(int a, int b) {
    return 1LL * a * b % mod;
}

int powm(int a, int b) {
    int r = 1;
    while (b) {
        if (b & 1) r = mul(r, a);
        b >>= 1;
        a = mul(a, a);
    }
    return r;
}


vector<int> edges[100005];
int n, m;
bool dfsFindPath(int u, int p, vector<int>& ppp) {
    if (u == m) {
        ppp.push_back(u);
        return true;
    }
    for (int v: edges[u]) if (v != p) {
        if (dfsFindPath(v, u, ppp)) {
            ppp.push_back(u);
            return true;
        }
    }
    return false;
}

int choose(int a, int b) {
    return mul(a, inv[b]);
}

pair<int, int> dfs(int u, int p, vector<int>& ppp, int ii) {
    if (u == m) return {1, 0};
    pair<int, int> s = dfs(ppp[ii], u, ppp, ii + 1);
    int t = edges[u].size();
    int p1 = mul(inv[t], s.first);
    int p21 = p == 0 ? choose(t - 1, t): choose(t - 2, t);
    p21 = mul(p21, choose(1, t - 1));
    p21 = mul(p21, s.first);
    int p22 = mul(choose(1, t), s.second);
    int p2 = add(
            p21, p22
            );
    return {p1, p2};
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t; cin >> t;
    for (int i = 1; i <= 100000; i++) {
        inv[i] = powm(i, mod - 2);
    }
    while (t--) {
        cin >> n >> m;
        for (int i = 0; i <= n; i++) edges[i].clear();
        for (int i = 0; i < n - 1; i++) {
            int a, b; cin >> a >> b;
            edges[a].push_back(b); edges[b].push_back(a);
        }
        vector<int> path;
        dfsFindPath(1, 0, path);
        reverse(path.begin(), path.end());
        pair<int, int> ret = dfs(1, 0, path, 1);
        cout << add(ret.first, ret.second) << "\n";
    }

}