Answer:
The correct punctuation of the sentence 
My sculpture had toppled over during the night _______ nevertheless, I picked up the pieces and packed them up for school.
is a:
D semicolon 
Step-by-step explanation:
In this case, we can observe that two ideas can be understood one without the other. So, they are not dependent. However, they complement each other. Nevertheless, we don't cut the general idea. Therefore, we only need a semicolon to separate them without breaking the meaning and topic.