E for me...
A is close, but TESTED THAT X and Y part is off, because it's unclear what exactly it was tested for
, and .... is the incorrect conjunction here. Makes the sentence somewhat stilted and choppy. Distorts the flow.
"that" clearly refers to the "jet engine".
(A) is succinct and clear.
@Apollo: No PC guru here has figured out how to copy and paste a file like that yet.