Which parts make up a fighting hole?

A fighting hole, also known as a foxhole, is designed to provide protection and a position for offensive or defensive engagement. The components mentioned in the correct answer, such as the parapet, elbow rest, fire step, grenade sump, and water sump, are essential for the functionality and effectiveness of a fighting hole in combat scenarios.

The parapet serves as a protective barrier for the personnel inside the fighting hole, helping to deflect enemy fire. The elbow rest offers comfort and support for the shooter while aiming, enhancing accuracy and reducing fatigue during prolonged engagements. The fire step allows combatants to elevate their position slightly, providing better visibility and strategic advantage when firing. The grenade sump is crucial for safely containing and deflecting the blast of thrown grenades, minimizing the risk to the occupants. Additionally, a water sump may be incorporated to manage drainage and prevent flooding within the hole during inclement weather.

These components are specifically tailored for operational combat scenarios, whereas the other options focus on different structures or features that do not align with the standard design of a fighting hole. For instance, walls and roofs are more characteristic of buildings or shelter, while access holes and observation points pertain to different concepts of defensive positioning.