What tools should be used to accomplish this?

A file is received daily from a data provider to the account SFTP. This file needs to be imported into Marketing Cloud as soon as it arrives. The arrival time of this file varies by several hours from day to day.

What tools should be used to accomplish this?
A . Journey Builder Fire Event Entry Source
B. Automation Studio Schedule Starting Source
C. Automation Studio File Drop Starting Source
D. Journey Builder Import Activity Entry Source

Answer: C