In which sentence does an adverb clause modify an adverb

A-When people did not understand the science behind an eclipse, they were afraid of the solar and lunar events.

B-The scientists studied the sun as the eclipse's shadow swept across Earth.

C-We used safety goggles when we viewed the eclipse.

D-A full lunar eclipse lasts longer than a partial eclipse

The answer is indeed letter D. A full lunar eclipse lasts longer than a partial eclipse.

Explanation:

In the sentence "A full lunar eclipse lasts longer than a partial eclipse" we can find an adverb, "longer", modifying the verb "lasts". The adverb itself is also modified by an elliptical adverb clause, "than a partial eclipse". This clause is elliptical because the verb that should appear in it is implied - the regular clause would be "than a partial eclipse lasts/does".

D: A full lunar eclipse last longer than a partial eclipse.

Explanation:

Because the adverb would be "longer" and the adverb clause would be "than a partial eclipse".