The core sentence after ignoring the inessential modifier is a compound sentence that is connected by the coordinate conjunction ‘
and’. Apparently, it looks as if the second part is simply a prepositional phrase, but actually, the intended sentence has an element of ellipsis, that is implicit
Will be able to deliver a heavier load of instruments into orbit than the space shuttle can, and (
will be able to deliver) at a lower cost.
It makes complete structural sense now and is parallel too logically. The ellipsis is not stated to avoid repetition In addition, the comparison between the two deliveries is matched with the use of the verb ‘can’
(E) A newly developed jumbo rocket, which is expected to carry the United States into its next phase of space exploration, will be able to deliver a heavier load of instruments into orbit than the space shuttle and to cost less.
The ellipsis doe not work well in E
will be able to deliver a heavier load of instruments into orbit than the space shuttle and (
will be able to deliver) to cost less. One can see the ellipsis does not make much sense. Secondly, the verb ‘can’ is missing and thus it becomes an illegitimate comparison between the rocket’s delivery and the shuttle.
All this is my gut feeling; even without the ellipsis, still D can be decided simply by virtue of parallel comparison of actions and E will simply fall by the way side
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Thank you Daagh for your time on GMAT Club and all your contributions! Thank you for everything you did!Your work will remain a great tribute to you here on GMAT Club!
-bb