Bunuel wrote:

Is \(x^2 + 9\) prime?

Official solution from

Veritas Prep.

What a tricky question!!! The lesson is to never assume that x is an integer unless it is stated.

Statement 1: (odd*odd) + odd = odd + odd = even. All even numbers are divisible by 2, so the statement is not prime. Statement 1 is sufficient.

Statement 2: 3<=x<=7. If you plug in x={3,4,5,6,7} you will see that all the results are divisible. However, x is not limited to integers. x can be pi, which will make this statement insufficient.

Since A is sufficient and B is insufficient, the answer is A.