#include<bits/stdc++.h>
#define N 100005
using namespace std;
const int P=1e9+7;
int f[N],g[N],fa[N],S[N],inv[N];
vector<int>a[N];
int n,m;
/*void DFS1(int x, int fa){
    int all = a[x].size();
    back[x] = inv[all];
    for (int i = 0; i < a[x].size(); i++){
        int y = a[x][i];
        if (y == fa) continue;
        DFS1(y, x);
        back[x] = (back[x] + 1ll*inv[all]*back[y]) % P;
    }
}*/
void DFS(int x){
    for (int i = 0; i < a[x].size(); i++){
        int y = a[x][i];
        if (y == fa[x]) continue;
        fa[y] = x; DFS(y);
    }
}
int main(){
    //printf("%d\n",6ll*666666672%P);
    inv[0]=inv[1]=1;for (int i=2;i<=100000;i++) inv[i]=1ll*(P-P/i)*inv[P%i]%P;
    int T; scanf("%d", &T);
    while (T--){
        scanf("%d%d",&n,&m);
        for (int i=1;i<n;i++){
            int x,y;
            scanf("%d%d",&x,&y);
            a[x].push_back(y);
            a[y].push_back(x);
        }
        DFS(1);
        *S=0;for (int i = m;i;i=fa[i]) S[++*S]=i;
        f[1]=1; g[1]=0;
        for (int t=*S;t;t--){
            int x=S[t],du=a[x].size(),mul=0;
            if (x==1) mul=1ll*(du-1)*inv[du]%P*inv[du-1]%P;
                else  mul=1ll*(du-2)*inv[du]%P*inv[du-1]%P;
            for (int i=0;i<a[x].size();i++){
                int y=a[x][i];if (y==fa[x]) continue;
                f[y]=1ll*f[x]*inv[a[x].size()]%P;
                g[y]=1ll*g[x]*inv[a[x].size()]%P;
                g[y]=(g[y]+1ll*f[x]*mul)%P;
            }
        }
        printf("%d\n",(f[m]+g[m])%P);
        for (int i=1;i<=n;i++) a[i].clear();
    }
}