一道prep数学DS题。。求大神解答。。

spinyfox

If w, x, y, and z are integers such that w/x  and y/z are integers, is w/x + y/z odd?
(1) wx + yz is odd.
(2) wz + xy is odd.

为什么选B而不选D呢。。。我怎么觉得（1）也是sufficient呢。。
求过程。。谢谢

spinyfox

实在不好意思之前有式子没粘上来。。。。不好意思。。

gorgeous

你确定题目没错？我怎么觉得是C涅？

1）肯定不对的，wx+yz is odd, one is even and the other is odd. The product of two is odd, that means both are odds. The product of two is even, that means one or both are even. So you cannot conclude that the sum of all four is odd.

2) is the same

If you combine all the criterea, that means among the all four, one is even, and the rest are all odds. And ths sume is odd.

That's why I choose C...