#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 3e5 + 10;
int a[N];
int gpre[N], gsuf[N];
void solve() {
    int n, k; cin >> n >> k;
    int o = 0;
    vector< int > id;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
        if(o != __gcd(o, a[i])) {
            id.push_back(i);
        }
        o = __gcd(o, a[i]);
    }
    a[n + 1] = 0;
    for(int i = 1; i <= n; i++) {
        gpre[i] = __gcd(gpre[i - 1], a[i]);
    }

    for(int i = n; i >= 1; i--) {
        gsuf[i] = __gcd(gsuf[i + 1], a[i]);
    }

    if(id.back() != n) {
        id.push_back(n);
    }
    int ans = 0;
    for(int i = 0; i < id.size(); i++) {
        int l = id[i]; int cur = gpre[l - 1];
        for(int r = l; r <= n; r++) {
            cur = __gcd(cur, a[r] + k);
            ans = max(ans, __gcd(cur, gsuf[r + 1]));
        }
    }
    for(int i = 0; i < id.size(); i++) {
        int r = id[i] - 1; int cur = gsuf[r + 1];
        for(int l = r; l >= 1; l--) {
            cur = __gcd(cur, a[l] + k);
            ans = max(ans, __gcd(cur, gpre[l - 1]));
        }
    }

    cout << max(o, ans) << '\n';
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int t= 1;
    cin >> t;
    while(t--)solve();
}