Data Sufficiency

vinayreguri wrote:IF x & y are integers , is (x^2-y^2) divisible by 4
i. x-y is even
ii. x+y is even

Statement 1: If (x - y) is even, then either x and y are both even or both odd.
In both the cases, (x + y) is also even.
Hence, (x² - y²) = (x - y)(x + y) = EVEN*EVEN = EVEN

Sufficient

Statement 2: If (x + y) is even, then either x and y are both even or both odd.
In both the cases, (x - y) is also even.
Hence, (x² - y²) = (x - y)(x + y) = EVEN*EVEN = EVEN

Sufficient

The correct answer is D.