A substance derived from the Madagascar periwinkle, which has proved useful in decreasing mortality among young leukemia patients, is cultivated in China as part of a program to integrate traditional herbal medicine into a contemporary system of health care.

(A) A substance derived from the Madagascar periwinkle, which has proved useful in decreasing mortality among young leukemia patients,
(B) A derivative, which has proved useful in decreasing mortality among young leukemia patients, of the Madagascar periwinkle,
(C) A Madagascar periwinkle derivative, which has proved useful in decreasing mortality among young leukemia patients,
(D) The Madagascar periwinkle has a derivative which has proved useful in decreasing mortality among young leukemia patients, that
(E) The Madagascar periwinkle, a derivative of which has proved useful in decreasing mortality among young leukemia patients,

Anyone with detailed explanation on why option E is wrong and what is the correct option.
Thanks