Answer:
According to the Purdue OWL, an independent clause is “a group of words that contains a subject and verb and expresses a complete thought.” A dependent clause is “a group of words that contains a subject and verb but does not express a complete thought.” Use a comma before a coordinating conjunction
Independent clause can stand on their own and come first, while the dependant clause (Depends on the independent clause) comes last
"Carla broke her back last week, after falling down the stairs."
"Carla broke her back last week" can stand on it's own, and "after falling down the stairs"cannot. so the correct answer is
A. The independent clause is first