SAT Question 6181924a: Boundaries answer and explanation

Choice B is the best answer. The convention being tested is the punctuation of an integrated relative clause within a sentence. No punctuation is needed between the noun phrase (“The natural and mechanical materials”) and the integrated relative clause (“that Palma Rodríguez uses in his art”). The integrated relative clause provides essential information about the materials, so no punctuation should separate it from the noun phrase it modifies. Additionally, no punctuation is needed between the sentence’s subject (“The natural and mechanical materials that Palma Rodríguez uses in his art”) and its main verb (“highlight”).