选择题
2014 AMC 8 Problem 13: Parity of Squares
If n and m are integers and n²+m² is even, which of the following is impossible?
2014 AMC 8 第13题 ：平方奇偶校验
如果n和m是整数， n ² m ²是偶数，以下哪项是不可能的？
A.
n and m are even
B.
n and m are odd
C.
n+m is even
D.
n+m is odd
E.
none of these are impossible