Sentence Correction

After more than four decades of research and development, a new type of jet engine is
being tested that could eventually propel aircraft anywhere in the world within two hours
or help boost cargoes into space at significantly lower costs than current methods permit.
A. tested that could eventually propel aircraft anywhere in the world within two
hours or help
B. tested that could eventually have the capability of propelling aircraft anywhere in
the world within two hours or to help
C. tested, eventually able to propel aircraft anywhere in the world within two hours,
or helping

D. tested, and it eventually could propel aircraft anywhere in the world within two
hours or helping
E. tested, and it could eventually have the capability to propel aircraft anywhere in
the world within two hours or help

pls explain

IMO A

THAT COULD ....PROPEL .....OR HELP (PARALLEL) So only A and E

that refers to engine so sounds better....engine that ....

Even I kept A as my answer but OA was E..

ppl, explain pls?

E is my pick. Usage of "that" makes it feel like "tested" is the one that is helping propel the aircraft, but it's the jet engine that will help propel.

After more than four decades of research and development, a new type of jet engine is
being tested that could eventually propel aircraft anywhere in the world within two hours
or help boost cargoes into space at significantly lower costs than current methods permit.

The fact that the engine is being Tested would not by itself cause the eventuality. The bold part makes this very mistake.

IMO E

I am totally confused between A and E.
According to me A is correct and "that" is correctly used.
Also in E 'it' might refer to research and development which is wrong.
Can someone plz provide better explaination

I would like to open this long sleeping thread again for the sake of discussion

In another forum,the same question has been posted with the OA A
However, while solving GMAT sets, I came up with this problem and the OA is E

Which indeed is the OA for the orginal poster of this thread.

I want to seek opinions from you guys. The contenders are A and E.

To me, E is also fine but the only problem is wordy and very awkward construction. I find A to be correct.

Express your views friends

i selected A bcos i always had this concept in my head that we cannot use and after a comma.....