Y has been believed to cause Z. A new report, noting that Y and Z are

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?
Boil it down - X may be the cause of Z (Y might be just a correlation) and X precedes Y and Z.

(A) In cases where X occurs but Y does not, X is usually followed by Z. - Y is absent and the order is what was need - Correct

(B) In cases where X occurs, followed by Y, Y is usually followed by Z. - Incorrect - we can conclusively say Y DOES NOT cause Z here

(C) In cases where Y occurs but X does not, Y is usually followed by Z. - Opposite -- so Z can occur even in the absence of X and Y-->Z

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

(E) In cases where Z occurs, it is usually preceded by X and Y. - Incorrect - does not help to zero in on the causality

Answer A