What is the purpose of the truck's differential?

Answer: B — To allow the wheels to rotate at different speeds when turning

The purpose of a truck's differential is critical in enhancing the vehicle's handling, particularly during turns. When a truck takes a corner, the wheels must travel different distances; the outer wheels cover more ground than the inner wheels. The differential allows for this difference in wheel rotation speeds, enabling smoother and more stable turning. Without a differential, both wheels would attempt to rotate at the same speed, leading to potential skidding or loss of control, especially on a turn. The other aspects mentioned, such as fuel efficiency, towing capacity, or braking system control, do not directly relate to the function of the differential. While improvements in handling can indirectly influence overall vehicle efficiency and performance, the primary role of the differential is to manage wheel speed variations during turns.