再问OG153

153. 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

Don't understand the explanation to E: ...and thus cannnot be logically connected to the remainder of the sentence.

so...that句式不使用E的表达方式。好像倒装也不是这么说的吧？！