Explanation

Creating a filter: the original sentence has defects. The phrase, "and estimated to be 27 million dollars" is set off by commas, but it's not a modifier, because it has the conjunction "and." Furthermore, the phrase can't be an independent clause, because it has no grammatical subject. A grammatical subject and its predicate may not be spliced by a single comma (such an error is called a "comma splice").

Applying the filter: We eliminate (A) and scan and see answer choice (C) has the same problem. We'll look for other grounds to eliminate further.

Finding objective defects: the other answer choices insert commas in an attempt to make the 1957 part into a legitimate modifier. Choice (B) introduces a pronoun with no reference, "they," so it's out. Answer choice (D) sounds good. Answer choice (E) is not grammatical. The relative pronoun "which" would have to be preceded by a comma here, since we have already defined what we are talking about and the modifier is only providing bonus information. Furthermore, it's awkward with a modifier inside a modifier. The correct answer is (D).