Sentence Correction

A recording system was so secretly installed and operated in the Kennedy Oval Office that even Theodore C. Sorensen, the White House counsel, did not know it existed.
(A) A recording system was so secretly installed and operated in the Kennedy Oval Office that
(B) So secret was a recording system installation and operation in the Kennedy Oval Office
(C) It was so secret that a recording system was installed and operated in the Kennedy Oval Office
(D) A recording system that was so secretly installed and operated in the Kennedy Oval Office
(E) Installed and operated so secretly in the Kennedy Oval Office was a recording system that

Answer: A

B - misses that
C - so..that emphasizes the wrong thing
D - Sentence formation is not correct
E - Close to the correct one. In fact i almost chose this. But, the emphasis is on the recording system. A correctly emphasizes the "secret installation"

OA is A

Looks like A is right