In what do you think the lack of gravity facilitated the astronauts work on the space ship?

answer: the first one

explanation:

explicitly is defined as “in a clear and detailed manner, leaving no room for confusion or doubt.” the rest are interpretive and not clearly proven leaving in fact possible “confusion or doubt” which explicitly, by definition cannot have.

i think the answer would mist likely be an adjective clause, because unhappy is an adjective.