Besides adding complementary flavors to many foods, hot sauces stimulate the release of
endorphins in the brain, just as exercise does, and these have a pain-relieving effect like
morphine's.
(A) hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these
have a pain-relieving effect like morphine's
(B) hot sauces stimulate the release of endorphins in the brain, like exercise, and they have a
pain-relieving effect that is like morphine
(C) hot sauces and exercise both stimulate the release of endorphins in the brain, and they have a
pain-relieving effect like morphine
(D) the release of endorphins in the brain is stimulated both by hot sauces and exercise, and they
have a pain-relieving effect like morphine's
(E) the release of endorphins in the brain is stimulated by hot sauces, just as with exercise, and
these have a pain-relieving effect like that of morphine

请问B选项they到底指代谁？ 答案说they指代不清。答案选A，那么A中的these又指代谁？these前面不也有好多复数名词吗？指代有什么原则吗？  

 谢谢  急问

请你把题号写上，

这个是大全的题目吧

另外把正确答案写上

正确答案是A 

我就是想知道A中的these 和B中的they 到底都可以指代谁？

(A) hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these
have a pain-relieving effect like morphine's
(B) hot sauces stimulate the release of endorphins in the brain, like exercise, and they have a
pain-relieving effect that is like morphine

prep后面的牛蹄啊！

AB的these/they指代由于前面都有两个名词可指，sauces/endorphins，所以在指代上他们无所谓优劣。比较后面，一个是like morphine's,另一个是 that is like morphine，高下立见。效果只能和吗啡的效果比，而不能和吗啡对比，因此B错了。

顺带说一句，指代上并不歧义。因为是and连接的两个主句，代词出现在后者的主语位置上，根据平行，这个代词优先指代前句的主语，指代endorphins的可能性非常小，因为它的语法作用只是一个介词的宾语。

they应该指代的是endorphins.