Which type of unloading involves a flexible approach based on the progress of the attack?

The type of unloading that involves a flexible approach based on the progress of the attack is tactical unloading. This process is designed to adapt in real-time to the evolving situation on the battlefield. Tactical unloading allows commanders to prioritize the unloading of supplies and personnel that are most critical to the immediate objectives, ensuring that resources align with the demands of the operation as it unfolds.

The flexibility of tactical unloading is essential in amphibious operations, where conditions can change rapidly due to enemy actions, weather, and other operational factors. This adaptability can involve decisions to unload specific units, vehicles, or equipment based on the dynamics of the attack, thereby enhancing the effectiveness and responsiveness of the operation.

In contrast, general unloading refers to a more standard approach that may not take real-time developments into account as closely, while selective unloading focuses on specific units or supplies rather than the overall situational context. Expedited unloading involves accelerating the unloading process but does not inherently consider the strategic necessity shaped by an ongoing attack. Thus, tactical unloading is the option that best represents a flexible and responsive strategy in an amphibious operation context.