#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define range(x) (x).begin(), (x).end()
const int dir[][2] = {1, 0, -1, 0, 0, 1, 0, -1};

#define int long long

const int N = 200005;
int f[2][20][N];
int n;

void pre(int f[][N], const vector<int> &a)
{
    for (int i = 1; i <= n; i++)
        f[0][i] = a[i];

    int t = __lg(n) + 1;
    for (int j = 1; j < t; j++)
        for (int i = 1; i <= n - (1 << j) + 1; i++)
            f[j][i] = gcd(f[j - 1][i], f[j - 1][i + (1 << (j - 1))]);
}

int ask(int f[][N], int l, int r)
{
    if (r < l)
        return 0;
    int k = __lg(r - l + 1);
    return gcd(f[k][l], f[k][r - (1 << k) + 1]);
}

vector<vector<int>> v;
void get(const vector<int> &a, bool flag)
{
    pre(f[flag], a);
    for (int i = 1; i <= n; ++i) {
        int pos = i;
        int now = a[pos];

        while (pos >= 1) {
            int l = 1, r = pos;
            while (l < r) {
                int mid = (l + r) >> 1;
                if (ask(f[flag], mid, i) != now)
                    l = mid + 1;
                else
                    r = mid;
            }
            v[i].push_back(l);
            pos = l - 1;
            now = gcd(now, a[pos]);
        }
    }
}
void solve()
{
    int k;
    cin >> n >> k;
    v.clear();
    v.shrink_to_fit();
    v.resize(n + 1);
    vector<int> a(n + 5), b(n + 5);
    for (int i = 1; i <= n; ++i)
        cin >> a[i];
    for (int i = 1; i <= n; ++i)
        b[i] = a[i] + k;

    pre(f[0], a);
    get(b, 1);

    for (int i = 1; i <= n; ++i) {
        sort(range(v[i]));
        v[i].erase(unique(range(v[i])), v[i].end());
    }

    int mx = 0;
    for (int i = 1; i <= n; ++i) {
        // cout << v[i].size() << '\n';
        for (const auto &c : v[i]) {
            int now = gcd(ask(f[0], 1, c - 1), gcd(ask(f[1], c, i), ask(f[0], i + 1, n)));
            mx = max(mx, now);
        }
    }

    cout << mx << '\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
    cin >> t;
    while (t--)
        solve();
    return 0;
}