Final answer:
To control an airplane's roll, the pilot will move the ailerons.
Step-by-step explanation:
If a pilot wants to control an airplane's roll, they would move the ailerons. Ailerons are control surfaces located on the wings of an airplane. When the pilot wants to roll the airplane, they will input commands through the control column or yoke, which will then move the ailerons to change the lift distribution across the wings, causing the airplane to roll.