Bunuel
The quartzite found in the Santa Ana Mountains is considered one of the most pristine Paleozoic mineral deposits,
believed to be metamorphosed since the deposition of the Triassic era.
(A) believed to be
(B) and it is believed to have been
(C) and that is believed to be
(D) which was, it is believed,
(E) which are believed to be
(A) believed to be
(B) and it is believed to have been
Option A and B are both grammatically correct but A is more concise than B hence considering A to be correct.
(C) and that is believed to be
This option is grammatically incorrect. The conjunction "and" requires a complete sentence to follow, but "that is believed to be" is not a complete sentence.
(D) which was, it is believed,
This option is grammatically incorrect and awkwardly phrased. The phrase "it is believed" is inserted in a way that disrupts the flow of the sentence.
(E) which are believed to be
This option is grammatically incorrect. The pronoun "which" should refer back to the singular noun "quartzite," so the verb "are" is incorrect. It should be "is."
(Reposting this as the old account is deactivated making the post null and void, pls do not report this post)