#include <iostream>
#include <atcoder/modint>
#include <set>
using namespace std;using M=atcoder::modint998244353;int main(){int T,N,L,n,m;cin>>T;while(T--){set<int> D;cin>>N>>L;for(m=0;m<N;m++){cin>>n;D.insert(n);}n=0;m=0;for(int d:D)if(L%2==0&&D.contains(d+L/2))n++;else m++;m-=n;M a;if(n<2)for(L=1;L<=N;L++)a+=N/M(L);else{M E1=N/M(n-1),E0=E1+N/M(n);for(L=1;L<n;L++){E1*=L*2/M(L+n-1);E1+=N/M(L+n-1);E0*=L*2/M(L+n);E0+=N/M(L+n);E0+=E1*(n-L)/(n+L);}a=N/M(2*n)+E0;}cout<<a.val()<<'\n';}return 0;}