Final answer:
When making a right turn and slowing down, it is important to check behind you to avoid colliding with vehicles.
Step-by-step explanation:
The correct answer is: c) To avoid colliding with vehicles behind you. When you slow down to make a right turn, it is important to check behind you to ensure there are no vehicles approaching from the rear. This helps you to avoid potential collisions and ensures the safety of both you and other drivers on the road.