#include<bits/stdc++.h>
typedef int LL;
typedef double dl;
#define opt operator
#define pb push_back
const LL maxn=1e6+9,mod=1e9+7,inf=0x3f3f3f3f;
LL Read(){
    LL x(0),f(1); char c=getchar();
    while(c<'0' || c>'9'){
        if(c=='-') f=-1; c=getchar();
    }
    while(c>='0' && c<='9'){
        x=(x<<3ll)+(x<<1ll)+c-'0'; c=getchar();
    }return x*f;
}
void Chkmin(LL &x,LL y){
    if(y<x) x=y;
}
void Chkmax(LL &x,LL y){
    if(y>x) x=y;
}
LL add(LL x,LL y){
    return x+=y,x>=mod?x-mod:x;
}
LL dec(LL x,LL y){
    return x-=y,x<0?x+mod:x;
}
LL mul(LL x,LL y){
    return 1ll*x*y%mod;
}
LL Pow(LL base,LL b){
    LL ret(1);
    while(b){
        if(b&1) ret=mul(ret,base); base=mul(base,base); b>>=1;
    }return ret;
}
struct node{
    LL to,nxt;
}dis[maxn];
LL T,n,m,num;
LL head[maxn],g[maxn],f[maxn],deg[maxn],fa[maxn],inv[maxn],dep[maxn];
void Add(LL u,LL v){
    dis[++num]=(node){v,head[u]}; head[u]=num;
}
void Dfs(LL u,LL ff){
    for(LL i=head[u];i;i=dis[i].nxt){
        LL v(dis[i].to);
        if(v==ff) continue;
        fa[v]=u; deg[v]=1; Dfs(v,u);
        deg[u]++;
    }
}
void Dfs1(LL u,LL ff){
    dep[u]=dep[ff]+1;
    for(LL i=head[u];i;i=dis[i].nxt){
        LL v(dis[i].to); if(v==ff) continue;
        f[v]=1ll*f[u]*inv[deg[u]]%mod; 
        if(deg[u]>1)
            g[v]=1ll*f[u]*(deg[u]-1-(ff!=0))%mod*inv[deg[u]]%mod*inv[deg[u]-1]%mod;
        g[v]=add(g[v],1ll*g[u]*inv[deg[u]]%mod);
        Dfs1(v,u);
    }
}
int main(){
    /*for(LL i=2;i<=30;++i){
        for(LL j=1;j<i;++j) if(mul(j,Pow(i,mod-2))==416666670) printf("%d/%d\n",j,i);
    }*/
    T=Read();
    for(LL i=1;i<=100000;++i) inv[i]=Pow(i,mod-2);
    while(T--){
        n=Read(); m=Read();
        for(LL i=1;i<n;++i){
            LL x(Read()),y(Read());
            Add(x,y); Add(y,x);
        }
        for(LL i=1;i<=n;++i) f[i]=g[i]=deg[i]=0;
        Dfs(1,0);
        f[1]=1;
        Dfs1(1,0);
        //if(dep[m]<=2) 
        printf("%d\n",add(f[m],g[m]));
        /*else{
            for(LL i=1;i<=n;++i)
            printf("%d,%d\n",dep[i],fa[i]);
            LL ans(add(f[m],g[m]));
            LL x(m);
            while(fa[x]!=1) x=fa[x];
            ans=dec(ans,1ll*inv[deg[1]]*inv[deg[x]]%mod);
            printf("%d\n",ans);
        }*/
        for(LL i=1;i<=n;++i) dep[i]=head[i]=0;
        num=0;
    }
    return 0;
}/*
1
5 4
1 2
1 3
3 4
3 5

*/