Which sentence contains an adverb clause?

AThe state of California is also called the Golden State.
BWhen you return from California, take a taxicab from the airport.
CYosemite National Park, in central California, covers nearly 1,200 miles of mountainous terrain.
DCalifornia has three of the top ten most populated cities in the United States.

Verified Answer :

An adverb clause is a dependent clause which cannot exist on its own, it has to be a part of the main, independent clause. So, having that in mind, the only dependent clause among these examples is 'when you return from California'. Therefore, the correct answer is B.