#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1010;
const int MOD = 1e9 + 7;
vector<int> e[MAXN];
bool vis[MAXN];
int g[MAXN][MAXN];
int l[MAXN], r[MAXN], size[MAXN], cnt[MAXN];
long long f[MAXN][MAXN];
int c[MAXN][MAXN];
long long f1[MAXN], f2[MAXN];
int tt;
void dfs(int v){
    vis[v] = true;
    size[v] = 1;
    for(size_t i = 0; i < e[v].size(); i++){
        int u = e[v][i];
        if(vis[u]) continue;
        dfs(u);
        if(!l[v]) l[v] = u;
        else {
            r[u] = l[v];
            l[v] = u;
            cnt[u] += cnt[r[u]];
        }
        size[v] += size[u];
    }
    cnt[v] = 1;
    if(l[v]) cnt[v] += cnt[l[v]];
}

void calc(int v, int p){
    if(g[v][p] == tt) return;
    g[v][p] = tt;
    if(!v || !p  || cnt[v] < p){
        f[v][p] = 0;
        return;
    }
    int i = 0;
    if(!r[v]) i = p;
    if(i) calc(l[v], i - 1);
    long long sum1 = 0, sum2 = 0;
    for(; i <= p; i++){
        calc(r[v], p - i);
        calc(l[v], i);
        if(!f[r[v]][p-i]) continue;
        if(i && f[l[v]][i-1]) sum1 = (sum1 + f[l[v]][i-1] * f[r[v]][p-i])% MOD;
        if(f[l[v]][i]) sum2 = (sum2 + f[l[v]][i] * f[r[v]][p-i])% MOD;
    }
    f[v][p] = (sum1 * f1[v] + sum2 * f2[v]) % MOD;
}

int main(){
    for(int i = 0; i < MAXN; i++){
        c[i][0] = 1;
        for(int j = 1; j <= i; j++) c[i][j] = (c[i-1][j-1] + c[i-1][j]) % MOD;
    }
    int T;
    scanf("%d", &T);
    for(tt = 1; tt <= T; tt++){
        int n, m;
        scanf("%d%d", &n, &m);
        for(int i = 1; i <= n; i++) e[i].clear();
        for(int i = 1; i <= n - 1; i++){
            int x, y;
            scanf("%d%d", &x, &y);
            e[x].push_back(y);
            e[y].push_back(x);
        }
        memset(vis, 0, sizeof(vis));
        memset(l, 0, sizeof(l));
        memset(r, 0, sizeof(r));
        dfs(1);
        f[0][0] = 1;
        g[0][0] = tt;
        for(int i = 1; i <= n; i++){
            f1[i] = c[cnt[i]][size[i]];
            f2[i] = f1[i] * (size[i]-1) % MOD;
        }
        /* for(int i = 1; i <= n; i++){
            cout << cnt[i] << ' ' << size[i] << endl;
        }
        */
        calc(1, m);
        /*
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= m; j++) cout << f[i][j] << ' ';
            cout << endl;
        }
        */
        printf("Case #%d: %I64d\n", tt, f[1][m]);
    }
    return 0;
}