The correct answer is "C."
The sentence is correct. It contains no error.
You have to write full sentences in order to write correctly. Let's remember that there are three kinds of sentences. A SImple sentence, that has one main clause. A compound sentence, that has at least two clauses that are connected by conjunctions and have their own subject and verb. And finally, complex sentences, that has one main clause, buy it is accompanied by one or more dependent clauses.