OG详解-OG7 文法 Q18

Choice C is the best answer. The convention being tested is punctuation use between a subject and a verb. No punctuation is needed when, as in this case, a subject (“Her portrait of novelist Zadie Smith”) is immediately followed by a main verb (“is displayed”). 
Choice A is incorrect because no punctuation is needed between the subject and the verb. Choice B is incorrect because no punctuation is needed between the subject and the verb. Choice D is incorrect because no punctuation is needed between the subject and the verb.