Please provide OA and source.

I can answer this one for you: this is a PrepScholar question, and the OA is B.

First off, we can eliminate C, D, and E. "and therefore may have studied the works of other cultures" must refer to "the early Greeks". However, in the last three answers, the subject of the sentence is "temples".

Deciding between A and B is trickier. When we have a pronoun in a sentence, it must refer to another noun in the sentence. In A, we have the plural pronoun "those". Reading the sentence, it would make the most sense for "those" to represent "temples": (e.g. The early Greeks designed a mud-brick temple that mirrored [the temples] of the Mesopotamians...). However, "temples" is not a word in our sentence. The only nouns that "those" can refer to are "Greeks" (which doesn't make sense) and "temple" (which is singular).

In B, on the other hand, "one" stands in for "temple", which does occur in the sentence (e.g. The early Greeks designed a mud-brick temple mirroring a Mesopotamian temple). So we eliminate A and choose B.

Be careful to ensure that all pronouns in your sentence refer to a word that is actually in the sentence - unless you're diligent, your brain will fill in a word that makes sense. This is a particularly nasty example (most pronoun issues will be easier to identify), but it's based on a real answer trap from a real GMAC problem.