The correct answer is A. Yesterday the professor said, "I will collect your papers tomorrow"; however, he never did collect them.
Explanation:
Semicolon (;) is a punctuation mark used for introducing pauses that are longer than in the case of the comma (,), but shorter than in the case of the period (.). Additionally, according to grammar semicolon is used to separate two independent clauses which are clauses that express a complete idea, also a semicolon should be placed before conjunctive adverbs such as moreover, therefore, finally, otherwise or however. Considering this, it is correct to place a semicolon before the word however, as the sentence presented contains two independent clauses "Yesterday the professor said, "I will collect your papers tomorrow" and "he never did collect them", and it is correct to separate them by a semicolon, also according to grammar before the conjunctive adverb "however" a semicolon should be placed.
