Answer: D) Semicolon.
Explanation: when we write a compound sentence (a sentence that have at least two independent clauses, with different verbs), we can separate the independent clauses in two ways: with a comma or with a semicolon. The comma is used when we have a coordinating conjunction between the clauses (like but, and, or, yet, etc). The semicolon is used in two cases, to separate two clauses that are closely related and when we have a Conjunctive Adverb (like accordingly, also, however, nevertheless, finally, etc), we place the semicolon before the adverb, so the given sentence will be: My sculpture had toppled over during the night; nevertheless, I picked up the pieces and packed them up for school.
