x and y are positive integers. If xy + 3x is odd, then which of the following must be even?	Select the correct option: A) x B) y C) 3 + y D) xy − x E) x^2 − y
Given that xy + x is odd, which means x(y+3) is odd.   Product of two nos. will be odd only if both the nos. are odd.   Hence x is odd, y+3 is also odd.   y+3 is odd means y is even. Answer will be 3 + y.
<result>C</result>
x and y are positive integers. If xy + 3x is odd, then which of the following must be even?