Data Sufficiency

anuptvm wrote:If x and y are positive integers, is y a prime number?

(1) xy is a prime number.

(2) y2 is even.

I assume this means y^2

Statement 1: xy is prime.
Therefore either (x is prime and y = 1) or (x = 1 and y is prime)

Not sufficient.

Statement 2: y^2 is even => y is even
y = 2 => y is prime
y = any other even integer => y is not prime

Not sufficient.

1 & 2 Together: From 2 consider y is an even integer other than 2, then statement 1 doesn't hold. Therefore y must be equal to 2. Thus y is prime.

Sufficient.

The correct answer is C.