Sentence Correction

This process resulted in a total of 15 new townships: of which, to date, 7 are still in existence.

(A) of which, to date, 7 are still in existence.
(B) of which number, 7 of the 15 are still, to date, in existence.
(C) of the number 15, 7, to date, are still in existence.
(D) to date of these 15, 7 are still in existence.
(E) to date, 7 of the 15 are still in existence.

OA is E
pls, can an Expert tell me what wrong with option A?