What best describes 'plunging fire'?

The term 'plunging fire' specifically refers to the trajectory of the rounds being fired from a lower elevation to a higher elevation, or from a higher elevation to a lower elevation. This type of fire takes advantage of the sloped terrain and can be particularly effective in ensuring that rounds strike the target at a steeper angle.

When employing plunging fire, the angle of descent allows for a more concentrated area of impact, improving the effectiveness against targets that may be behind cover or at varying elevations. This concept is critical in understanding how to leverage terrain for maximum impact, especially in military tactics involving machine guns.

The other choices describe different firing scenarios but do not accurately encapsulate the nature of plunging fire. For example, fire on level ground is straightforward and lacks the benefits offered by changes in elevation. Similarly, short bursts of fire pertain more to the firing technique rather than the trajectory involved in plunging fire. Lastly, while some types of fire may not require elevation adjustments, this characteristic does not define plunging fire, which specifically involves different elevation levels.