请教大全中的一道题

我都不明白整个题在说什么,晕!请高手指点

12.   Y has been believed to cause Z. A new report, noting that Y and Z are often observed to be preceded by X, suggests that X, not Y, may be the cause of Z.

Which of the following further observations would best support the new report’s suggestion?

(A) In cases where X occurs but Y does not, X is usually followed by Z.

(B) In cases where X occurs, followed by Y, Y is usually followed by Z.

(C) In cases where Y occurs but X does not, Y is usually followed by Z.

(D) In cases where Y occurs but Z does not, Y is usually preceded by X.（A）

(E) In cases where Z occurs, it is usually preceded by X and Y.

不是高手，试着解释一下：

题干: Y曾经被认为是Z的原因. 新报告指出,Y和Z经常在X后,所以可以得出可能X(不是Y)是Z的原因.

问题: 问support,即加强结论. A:X发生时Y不发生, 且Z通常跟在X后面.

原因在前,结果在后.

个人理解,请NN指正.