A) The lemurs called out and clamored a full 15 minutes prior to the quake.

B) The lemurs called out and clamored for a full 15 minutes prior to the quake.

1. Are both of the above sentences fine?

2. If only A) is right, is 'a full 15 minutes' an objective or an adverb?

Thank you for your help.
lucas21cA) The lemurs called out and clamored a full 15 minutes prior to the quake.
B) The lemurs called out and clamored for a full 15 minutes prior to the quake.
1. Are both of the above sentences fine?
Yes. Both are fine.

CJ
Thank you, CalifJim. By the way, 'a full 15 minutes' of A) is an adverb?
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lucas21cThank you, CalifJim. By the way, 'a full 15 minutes' of A) is an adverb?

Yes. It answers the question "How long?" so it's an adverb of time.

In reality it's a noun phrase because minutes is a noun, but it functions in the sentence as a way of saying how long the lemurs made their noises so it acts like an adverb acts.

CJ