#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <vector>

using namespace std;

#define rep(i, l, r) for(int i=l; i<=r; i++)
#define dow(i, l, r) for(int i=l; i>=r; i--)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define clr(x, c) memset(x,c,sizeof(x))

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> Pii;

inline int read()
{
    int x=0,f=0; char ch=getchar();
    while (ch<'0' || '9'<ch) f|=ch=='-', ch=getchar();
    while ('0'<=ch && ch<='9') x=x*10+ch-'0', ch=getchar();
    return f?-x:x;
}

#define maxn 100009
#define maxm 200009

struct edge {int x, y; edge *n;} e[maxm], *fir[maxn], *pt=e;
inline void addEdge(int x, int y) {
    pt->x = x; pt->y = y; pt->n = fir[x]; fir[x] = pt++;
    pt->x = y; pt->y = x; pt->n = fir[y]; fir[y] = pt++;
}
#define travel(x) for(edge *p=fir[x]; p; p=p->n)

#define Q 1000000007
int dis[maxn], fa[maxn], f0, f1, p[maxn];

void dfs(int x) {
    travel(x) if (p->y != fa[x]) {
        dis[p->y] = dis[x] + 1;
        fa[p->y] = x;
        dfs(p->y);
    }
}

void dfs2(int x) {
    if (fa[x]) {
        dfs2(fa[x]);
        int tot = 0, cnt = 0;
        travel(fa[x]) {
            tot += 1;
            if (p->y != x && p->y != fa[fa[x]]) cnt += 1;
        }
        f1 = (1LL * f0 * cnt % Q * p[tot] % Q * p[tot-1] % Q + 1LL * f1 * p[tot] % Q) % Q;
        f0 = 1LL * f0 * p[tot] % Q;
    }
}

inline int pow(int x, int t) {
    int g = 1;
    while (t) {
        if (t&1) g = 1LL*g*x%Q;
        x = 1LL*x*x%Q;
        t >>= 1;
    }
    return g;
}

int main() {
    rep(i, 1, 100000) p[i] = pow(i, Q-2);
    int T = read(); while (T--) {
        int n = read(), m = read();

        // init();
        rep(i, 1, n) fir[i] = 0;
        pt = e;
        rep(i, 1, n) dis[i] = fa[i] = 0;

        rep(i, 1, n-1) {
            int x = read(), y = read();
            addEdge(x, y);
        }
        dis[0] = 0;
        dfs(1);
        f0 = 1;
        f1 = 0;
        dfs2(m);
        printf("%d\n", (f0+f1) % Q);
    }
}