#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <math.h>
using namespace std;
const int mod = 1000000007;
int rd[100005];
bool vis[100005];
bool flag[100005];
vector<vector<int> > G;
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n,m,k;
        scanf("%d%d%d",&n,&m,&k);
        G.clear();
        G.resize(n+5);
        memset(vis,0,sizeof(vis));
        memset(flag,0,sizeof(flag));
        memset(rd,0,sizeof(rd));
        while(m--)
        {
            int l,r;
            scanf("%d%d",&l,&r);
            G[l].push_back(r);
            rd[r]++;
        }
        priority_queue<int,vector<int>,greater<int> > q;
        for(int i=1;i<=n;i++)
        {
            if(rd[i]<=k)
            {
                vis[i]=1;
                q.push(i);
            }
        }
        long long _i=1;
        long long res=0;
        while(!q.empty())
        {
            int v=q.top();
            q.pop();
            vis[v]=0;
            if(rd[v]>k) continue;
            flag[v]=1;
            //cout<<v<<endl;
            res+=_i*(long long)v;
            _i++;
            res%=mod;
            k-=rd[v];
            for(int i=0;i<G[v].size();i++)
            {
                int e=G[v][i];
                rd[e]--;
                if(rd[e]<=k&&!vis[e]&&!flag[e])
                {
                    vis[e]=1;
                    q.push(e);
                }
            }
        }
        for(int i=1;i<=n;i++)
        {
            if(rd[i]==0&&!flag[i]) q.push(i);
        }
        while(!q.empty())
        {
            int v=q.top();
            q.pop();
            //cout<<v<<endl;
            res+=_i*(long long)v;
            _i++;
            res%=mod;
            for(int i=0;i<G[v].size();i++)
            {
                int e=G[v][i];
                rd[e]--;
                if(rd[e]==0)
                    q.push(e);
            }
        }
        cout<<res<<endl;
    }
}