Sentence Correction

The development of a new jumbo rocket that 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 at a lower cost.

(A) The development of a new jumbo rocket that 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 at a lower cost.
(B) The development of a new jumbo rocket is expected to carry the United States into its next phase of space exploration and be able to deliver a heavier load of instruments into orbit at a lower cost than the space shuttle.
(C) The new development of a 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 at a lower cost than the space shuttle.
(D) 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 can, and at a lower cost.
(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.

OA D

I know that this question has been covered before, but I don't understand how the comma before the "and" in D is correct. Shouldn't the clause following the comma + "and" be independent? I understand why all the other answers are incorrect.

The source of this question is the OG 11th edition.

If we rewrite the sentence in simpler terms, it would look like this:

The new rocket will be able to deliver a heavier load, and at a lower cost.

The implied meaning is:

The new rocker will be able to deliver a heavier load, and be able to deliver it at a lower cost.

Isnt the meaning distorted in D.

It is the development which will carry US to next level, rather than the rocket itself? as per the original statement.