Answer: C- "Although rain was drenching the players, the players still finished the game."
Step-by-step explanation:
An adverbial clause is a dependent clause that changes the main verb in the independent clause. They will always start with a subordinating conjunction (although, because, before, etc) and must connect to an independent clause to make sense.
For example: Even if I take the train, I still might be late to my appointment
For example: After the storm passed, we went outside.
In these sentences, the adverbial clauses in italics modify the latter independent clauses. If you're confused by what an adverbial clause is, just look for the sentences that start with these subordinating conjunctions.
Hope this helps!