If n is a positive integer, which of the following expressions must be even?
Choose the most appropriate option.
A) (n − 5)( n + 3)
B) (n − 6)( n + 3)
C) (n − 6)( n + 8)
D) (n − 7)( n + 5)
E) (n − 9)( n + 11)
Whether n is even or odd, (n-6)(n+3) will have one odd factor and one even factor.   The product will be even.   The answer is (n − 6)( n + 3).
<result>B</result>
If n is a positive integer, which of the following expressions must be even?