What would be necessary to control movement if the engine could not safely stop within required distance?

To control movement effectively if the engine cannot safely stop within the required distance, coupling air hoses and charging brake systems is critical. This action is necessary because it enhances the braking capability of the train by enabling the air brake system to function optimally. By ensuring that the brake systems are fully charged, the crew can apply brakes more effectively to bring the train to a safe stop, even if initial stopping distances are insufficient.

This option directly addresses the need for improved braking power, which is essential in a scenario where stopping is not achievable in the traditional manner. Ensuring that air hoses are coupled and that brakes are charged not only boosts control over the train's movement but also reinforces the overall safety measures required in switching operations.

The other choices, while they may involve aspects of train operation or engine control, do not primarily focus on enhancing the braking capability to address the specific issue of inadequate stopping distance.