The expression rs+r is odd when the r and s are integers. Which of the following expressions must be even? Choose the correct answer:
A) r  B) s  C) r + s  D) rs - r  E) r + s^2
rs+r is odd   r and s are integers   If r were even rs+r would be even despite any value of s.   s can't be odd, so s must be even.   Ans : s
<result>B</result>
The expression rs+r is odd when the r and s are integers. Which of the following expressions must be even?