Should not the answer be B.
x^2 - y^2 = (x+y)(x-y)
Statement 2 says that x+y is divisible by 8. In that case (x+y)(x-y) is also divisible by 8.
Ok, the trick is: the number is divisible by X if after division there is integer left and no remainder.
In this question, answer 2 precludes the situation when x=7.77, y = 0.23, so
(x+y)(x-y)/8 = integer*7,52
thus we need answer 1 and answer 2 to make sure that after division by 8 we'll end up with multiplying two integers.