Each one of the following sentences contains a clause. In which sentence is the clause used as an adverb?
a. What you really need is a back massage.
b. Whales, which eat krill, prefer colder ocean waters.
c. All of the delegates who have actual opinions should keep silent.
d. I do not mind fishing, as long as I don't have to bait the hook.

Respuesta :

b. Whales, which eat krill, prefer colder ocean waters.

Clauses are fragments in a sentence or collection of words which have a subject and predicate compared to phrases. Adverbial clauses are type of clauses that act and form as an adverb in a given sentence.
In the given sentence the adverbial clause is 
which eat krill.