What is required during MATC operation after a full stop?

During MATC (Manual Automatic Train Control) operation, after a full stop, it is essential to activate the ATC Start button. This action is critical because it signals the train control system to transition the train back into an automatic operation mode, enabling it to resume service safely and effectively. Activating the ATC Start button is part of the standard operational procedures and ensures that the appropriate safety protocols are followed before the train moves again.

The other options, while they may include important protocols in various circumstances, do not directly pertain to the immediate actions required after a full stop in the context of MATC operation. For instance, performing a manual inspection or notifying the trainmaster may be necessary under different circumstances but are not the primary actions required immediately after a stop. Checking passengers for safety is also crucial but is typically addressed at different operational stages rather than being a direct step in resuming MATC operation. Thus, the focus on the ATC Start button is a fundamental aspect of safely restoring the train's operation.