OG详解-OG9 文法 Q3

Choice B is the best answer. The convention being tested is pronoun–antecedent agreement. The plural pronoun “they” agrees in number with the plural antecedent “woodcuts” and clearly identifies what was exhibited at the Smithsonian American Art Museum.
Choice A is incorrect because the singular pronoun “it” doesn’t agree in number with the plural antecedent “woodcuts.” Choice C is incorrect because the singular pronoun “this” doesn’t agree in number with the plural antecedent “woodcuts.” Choice D is incorrect because the plural pronoun “some” is illogical in this context(referring to “some” of two woodcuts).