NMNMX

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
 ll crr[5005][5005]={0};

 //*****************************************************************************

 ll modInv(ll a,ll m=1000000007)
 {
        ll m0 = m;
        ll y = 0, x = 1;
        if (m == 1)
                return 0;
        while (a > 1){
                // q is quotient
                ll q = a / m;
                ll t = m;
                // m is remainder now, process same as
                // Euclid's algo
                m = a % m, a = t;
                t = y;
                // Update y and x
                y = x - q * y;
                x = t;
        }
        // Make x positive
        if (x < 0)
    {
       x += m0;
    }
        return x;
}

ll modDivide(ll a,ll b,ll m=1000000007)
{
       // a = a % m;
        ll inverse= modInv(b,m);
        return (inverse*a)%m;
}


//******************************************************************************

ll modex(ll x,ll y,ll lebhai)
{
    if(y<=0)
        return 1;
    else if(y%2==0)
        return modex((x%lebhai*x%lebhai)%lebhai,y/2,lebhai);
    else
        return (x%lebhai*(modex((x%lebhai*x%lebhai)%lebhai,(y-1)/2,lebhai))%lebhai)%lebhai;
}
int main()
{ ios_base::sync_with_stdio(false);
    cin.tie(NULL);
ll t,p=1000000006;


for (ll i = 0; i <= 5000; i++)
    {
        for (ll j= 0; j <= i; j++)

         {

            if (i == j||j == 0  )
                {crr[i][j] = 1;
                }

            else
                 {crr[i][j] =  (crr[i-1][j-1] + crr[i-1][j])%p;
    }}

}
         cin>>t;
         while(t--)
         {

         ll n,k,it,in,pr=1,p3,p4,p2;
         cin>>n>>k;
         ll a[n];
         for(it=0;it<n;it++)
         {
             cin>>a[it];
         }
         sort(a,a+n);
         // if(n%2!=0)
     //  {
        for( in=1;in<n-1;in++)
        { p2=(n-in-1)>=(k-1)? crr[n-in-1][k-1]:0;
         p3=(in>=(k-1))?crr[in][k-1]:0;
        p4=((n-1)>=(k-1))?crr[n-1][k-1]:0;

         ll ans1=modex(a[in],p4%p,1000000007);
           ll ans2=modex(a[in],((p2+p3)%p),1000000007);
          pr= (pr%1000000007*(modDivide(ans1,ans2,1000000007))%1000000007)%1000000007;
          // b[in]=(p4- p2-p3)%1000000006;
           // b[n-in-1]=b[in];
        }
      // }
  /*else
       {

            for( in=1;in<=(n/2)-1;in++)
           { p2=(n-in-1)>=(k-1)? crr[n-in-1][k-1]:0;
         p3=(in>=(k-1))?crr[in][k-1]:0;
         p4=((n-1)>=(k-1))?crr[n-1][k-1]:0;
          // b[in]=(p4- p2-p3)%1000000006;
          //  b[n-in-1]=b[in];
        }

       }*/
  /*for( in=1;in<=n-2;in++)
            {cout<<b[in]<<" ";
        }
cout<<"hello\n"<<endl;*/
        /*  for(in=1;in<n-1;in++)
       {
           ll ans1=modex(a[in],p4,1000000007);
           ll ans2=modex(a[in],((p2+p3)%p),1000000007);
          pr= (pr%1000000007*(modDivide(ans1,ans2,1000000007))%1000000007)%1000000007;
           //(pr%1000000007*(modex(a[in],b[in],1000000007))%1000000007)%1000000007;
       }*/
       cout<<pr<<endl;

    }
    return 0;

}