x and y are positive integers. If xy + x is even, then which of the following must be even?	Options.
A) x
B) y
C) x + y
D) y+1
E) x^2 − y
Given that xy + x is even, which means x(y+1) is even.   Product of two nos. will be even only if both the nos. are odd.   Hence x is odd, y+1 is also even.   y+1 is even. Answer will be y+1.
<result>D</result>
x and y are positive integers. If xy + x is even, then which of the following must be even?