What type of modern action involves multiple moving parts controlled by the user?

The correct answer encompasses all the listed types of actions—break action, pump action, and semi-automatic action—understanding that each of these mechanisms involves moving parts that the user actively controls during operation.

Break action firearms operate by pivoting open to reload, allowing the user to manually insert cartridges before closing the action to prepare for firing. This process requires user engagement to function correctly.

Pump action firearms involve a sliding forend that the user must pull back and then push forward to chamber a round. The movement of this forend activates the firearm's feeding mechanism, illustrating the user's control over multiple moving components.

Semi-automatic action firearms utilize the energy generated by the firing round to automatically cycle the action; however, the user must still pull the trigger for each shot, which involves active engagement with the firearm's mechanics.

Therefore, the answer reflects the understanding that each of these types of firearms require the user to interact with their respective moving parts during operation.