In combat, why is it important to have a parapet around a fighting position?

Having a parapet around a fighting position is crucial because it offers additional protection against enemy fire. The parapet acts as a shield, absorbing or deflecting incoming rounds and shrapnel, which enhances the survivability of the personnel within the fighting position. This focused protection helps ensure that Marines can withstand enemy attacks while maintaining their operational effectiveness.

While the other options highlight various aspects of a fighting position, they do not directly contribute to the primary defensive purpose of a parapet. Although a vantage point for observation is essential, it is not the primary function of a parapet. Similarly, while easier movement and storage areas may be functional benefits, they don't represent the critical protective aspect that a parapet provides, which is vital for operational success and troop safety in combat scenarios.