If n is a positive integer, which of the following expressions must be even? Pick one:	A) (n − 1)( n + 1)	B) (n − 4)( n + 1)	C) (n − 2)( n + 6)	D) (n − 5)( n + 1)	E) (n − 3)( n + 3)
Whether n is even or odd, (n-4)(n+1) will have one odd factor and one even factor.   The product will be even.   The answer is (n − 4)( n + 1).
<result>B</result>
If n is a positive integer, which of the following expressions must be even?