#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const LL p = 1E9 + 7;
LL qpow(LL a, LL b) {
    if (!b) return 1;
    LL t = qpow(a, b >> 1);
    t = t * t % p;
    if (b & 1) t = t * a % p;
    return t;
}

const int N = 1E5 + 5;
int n, m, fa[N];
vector <int> a[N];
void dfs(int x) {
    for (int i = 0; i < (int)a[x].size(); i++) {
        if (fa[a[x][i]] == -1) {
            fa[a[x][i]] = x;
            dfs(a[x][i]);
        }
    }
}

void solve() {
    scanf("%d %d", &n, &m);
    for (int i = 1; i <= n; i++) a[i].clear();
    for (int i = 2; i <= n; i++) {
        int x, y;
        scanf("%d %d", &x, &y);
        a[x].push_back(y);
        a[y].push_back(x);
    }
    
    memset(fa, -1, sizeof fa);
    fa[1] = 0;
    dfs(1);
    
    vector <int> deg;
    while (true) {
        m = fa[m];
        if (m) deg.push_back((int)a[m].size());
        else break;
    }
    reverse(deg.begin(), deg.end());
    
    LL ans = 0;
    for (int i = -1; i < (int)deg.size(); i++) { // distract at i
        if (i == 0 && deg[i] == 1) continue;
        if (i >= 1 && deg[i] == 2) continue;
        LL tmp = 1;
        for (int j = 0; j < (int)deg.size(); j++) {
            if (j == i) {
                if (i == 0) tmp *= qpow(deg[i], p - 2);
                if (i >= 1) tmp *= 1LL * (deg[i] - 2) * qpow(deg[i] * (deg[i] - 1) % p, p - 2 ) % p;
            }
            else tmp *= qpow(deg[j], p - 2);
            tmp %= p;
        }
    //    cerr << i << ": " << tmp << endl;
        ans += tmp;
    }
    printf("%lld\n", ans % p);
}
int main() {
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}