Meaning Analysis:The sentence conveys that one A caused B and the final result is C.
A is Big Bang; B is expansion; C is galaxies rushing outwards
Error Analysis:A) The preeminent astronomer, Carl Sagan, posited that the expansion of the universe,
with galaxies rushing ever outward away from each other, was caused by the Big Bag about 15 billion years ago.
(with galaxies rushing outwards seems like it is modifying expansion of the universe. This is not the case. A caused B, resulted in galaxies rushing outwards..)B) The preeminent astronomer, Carl Sagan, posited that the expansion of the universe, with galaxies rushing ever outward away from each other, is caused by the Big Bag about 15 billion years ago.
(Same as A)C) Carl Sagan, the preeminent astronomer, posited that the expansion of the universe was caused by the Big Bang about 15 billion years ago
and the galaxies are rushing ever outward away from each other.
(and suggests that expansion was caused by both Big bang and galaxies rushing outwards. This is not correct)D) The preeminent astronomer, Carl Sagan, posited that the Big Bang caused the expansion of the universe about 15 billion years ago, sending the galaxies rushing eve outward away from each other.
(Aha. Correct as described by meaning analysis)
E) The preeminent astronomer, Carl Sagan, posited that the Big Bang, causing the expansion of the universe about 15 billion years ago, sending the galaxies rushing ever outward away from each other.
(causing the explosion .... sending the galaxies is not parallel and distorts the intended meaning. Big bang caused the expansion which resulted in galaxies rushing outwards)