If the rear wheel locks, what is the appropriate action?

Answer: C — Not release the brake

When the rear wheel locks while riding a motorcycle, the recommended action is to not release the brake. This is crucial because locking the rear wheel can result in a loss of control, and releasing the brake might allow the rear wheel to begin to spin again, which can lead to instability and increase the risk of a crash. Instead, the rider should maintain pressure on the rear brake and actively manage the situation, which may involve easing off the brake slightly to allow for control while keeping the situation stable. Using the front brake appropriately and shifting weight toward the front can help regain control, but it is essential to keep the rear brake applied to maximize stability. This approach helps the rider maintain control while addressing the issue of the locked wheel.