OG详解-OG6 文法 Q16

Choice C is the best answer. The convention being tested is end-of-sentence punctuation. This choice correctly uses a question mark to punctuate the coordinated interrogative clauses “What are atmospheric rivers” and “how do they affect our weather,” both of which ask direct questions.
Choice A is incorrect because a period can’t be used in this way to punctuate an interrogative clause, such as “how do they affect our weather,” at the end of a sentence. Choice B is incorrect because the structure requires an interrogative clause and a question mark at the end of the sentence. Choice D is incorrect because the structure requires an interrogative clause at the end of the sentence.