Explanation:

Let’s break down each option:

- 1, 1001: Both are palindromic numbers—you can read them the same forwards and backwards.

- 715: This is a binomial coefficient (combinatorial number), specifically 13C3 (13 choose 3).

- 429: Another binomial coefficient, this is 9C4 (9 choose 4).

- 390: This number doesn't match the pattern. It’s not palindromic, nor is it a binomial coefficient commonly recognized in this set.

Here’s what this really means: Options 2 and 3 are clear binomial coefficients. Option 1’s numbers are palindromes, which ties them together. But 390? It stands out—it doesn’t follow either of those patterns.

So, the answer is:

Option:4 - 390