Hi candygal79,

This DS question is built on Number Properties.

We're told that X and Y are PRIME numbers. We're asked if "Y(X-3) is odd?" This is a YES/NO question.

Here are the Number Properties worth knowing for this question:
Odd x Odd = Odd
Even x Odd = Even
Even x Even = Even

Fact 1: X > 10

Since X is PRIME and X > 10, this means that X MUST be ODD. Furthermore, this means that (X-3) MUST be EVEN. Notice that ANY integer multiplied by an EVEN yields an EVEN? So Y(X-3) will NEVER be ODD. This is CONSISTENT.
Fact 1 is SUFFICIENT

Fact 2: Y < 3

Since Y is PRIME, it Y MUST be 2. Here, we're dealing with the SAME Number Property rule as in Fact 1: Since Y is 2, 2(X-3) MUST be EVEN, so it will NEVER be odd. This is CONSISTENT.
Fact 2 is SUFFICIENT

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

Rich's solution is great, so I won't say anything more about that.

I will say that GMAT questions featuring PRIME numbers are often testing your ability to recognize that not all prime numbers are odd.
There are many people who assume that 2 is not prime since it's even. However, an integer is prime if it has exactly 2 positive divisors. The positive divisors of 2 are 1 and 2, so 2 must, indeed, be prime. So, in reality, all prime numbers are odd with the exception of 2, which is even.

Cheers,
Brent