Which sentence contains an adverb clause? a. the declaration of independence was also proclaimed in trenton, new jersey, and in philadelphia. b. i studied that when i was in sixth grade. c. can you name ten of the signers of the declaration of independence? d. on july 8, 1776, the declaration of independence was read aloud in easton, pennsylvania's centre square.

The correct answer is A) I studied that when I was in sixth grade. In this independent sentence, the adverb clause is 'when I was in sixth grade'. An adverb clause is a subgroup of dependent clauses, meaning that it cannot exist on its own, outside of the main, independent clause. Just saying 'when I was in sixth grade' means nothing, it is incomplete.
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B. I studied that when i was in 6th grade