* Speculation/May

[nitd2k]

There is speculation that increasing cold weather was what may have been responsible for the Anasazi move from Mesa Verde to sites in other canyons.
(A) that increasing cold weather was what may have been
(B) whether increasing cold weather was what was
(C) that increasingly cold weather was what had been
(D) whether increasingly cold weather may have been what was
(E) that increasingly cold weather may have been

Credited answer is E.I want to know if it is correct to use MAY when SPECULATION is already present denoting the probabilistic nature.

[Ben Ku]

Please cite the source (author) of this problem. We cannot reply unless a source is cited (and, if no source is cited, we will have to delete the post!). Thanks.