Adverbs refer to the words which modify the verb, adjectives or adverbs, expressing a relation of a cause, time, place and so forth.
Whereas, an adverb clause refers to the group of words which works as an adverb. An adverb clause begins with the subordinating conjunction such as if, although, because and so forth. Lastly, it includes subject and predicate.
Therefore, the sentence which does an adverb clause modify a verb is, We saluted because the flag had been raised.
In the above sentence, "because the flag had been raised" modifies the verb "saluted."
