I think it’s subordinate since it can’t stand on its own. Subordinates add more information to the sentence.
Answer:
The warm, vibrant room evaporates into a brisk, solitude.
Explanation
Look up words to make the sentence more awake. Try the Thesaurus. Try embedding the one sentence I typed into your sentence it could work. Maybe come up with other words.
I believe b, because then is considered a transition word
"David throws" is the one among the following choices given in the question that is the independent clause. The correct option among all the options that are given in the question is the second option or option "B". An independent clause always has a subject and a predicate. I hope the answer has helped you.