[求助]一道high-score中的题

In the nature reserve of India, people are sometimes atackted by tigers, and it is believed tigers only attack people from behind, so for the last few years many workers in the nature have started to wear clothes depicting human face on the back of their heads. while the local residents specticisim, no one wearing the mask has been yet attacked by tigers.

which following supported the argument of those who advocate wearing mask?

A.Many workers in the nature reserve who didnot wear the mask were attacked by tigers recently.

B Workers in other nature reserves who wear the similar mask have not been attacked by tigers.

我认为这两个答案都是对的，既然是支持，不需要是必要条件，B给处在同样的条件下得出同样的结果，和A中的非A---->非B 都可以support结论嘛，它们之间还有优先级吗。

（祥题见high score 中的goto-tests-CR tests3 No.4 ）