#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
    int T;
    scanf("%d", &T);
    for(int ii = 0; ii < T; ++ ii) {
        int n; int m; int k;
        scanf("%d%d%d", &n, &m, &k);
        vector<vector<int> > g(n);
        vi deg(n);
        for(int i = 0; i < m; ++ i) {
            int u, v;
            scanf("%d%d", &u, &v), -- u, -- v;
            g[u].push_back(v);
            ++ deg[v];
        }
        priority_queue<int,vi,greater<int> > q;
        rep(i, n) if(deg[i] <= k)
            q.push(i);
        vector<bool> used(n, false);
        ll anssum = 0;
        rep(t, n) {
            int i;
            while(1) {
                i = q.top(); q.pop();
                if(!used[i] && deg[i] <= k)
                    break;
            }
            anssum += (ll)(t + 1) * (i + 1);
            k -= deg[i];
            used[i] = true;
            each(j, g[i]) if(!used[*j]) {
                if(-- deg[*j] <= k)
                    q.push(*j);
            }
        }
        printf("%d\n", (int)(anssum % 1000000007));
    }
    return 0;
}