求助一道prep 题，

各位: 帮我看看这道题吧。

 if M is a finite set of negative integers ,is the total numberof intergers in M an odd number

1) the product all of all the intergers in M is odd

2) the product of all the intergers in M is negative

the answer is B , which confused me .,thanks for your help for this question

A. the result of all product inside the set 是奇还是偶不可以推出 total number 是奇还是偶

B is correct.  If even number of negative integer 相成的话,得正数. If odd number of negative integer 相成的话,得负数. B 足够.

恩，明了！ 多谢拉