When revising a theses statement you should consider numerous things. For starters, whether it makes sense and is connected to your introduction paragraph. Make sure that everything you mention in your thesis has to be elaborated, you can't leave things unexplained. Also, make sure that you have enough supporting arguments and research potential.
Answer:
his little tool boxes as well—they were treasures
Explanation:
A.It is an adverb clause modifying set.
Explanation: