Which of the following represents a primary threat from adversarial ground forces?

The primary threat from adversarial ground forces is represented by teams firing mortars or rockets into friendly compounds. This type of threat is direct and immediate, as it involves the ground forces actively targeting positions where friendly troops are located, potentially causing significant damage and casualties. Mortar and rocket attacks can be launched from relatively short distances and are difficult to detect before they impact, making them a particularly dangerous form of attack in combat scenarios.

While high altitude bombing runs, electronic warfare tactics, and unmanned aerial vehicles are indeed threats that can be posed by adversaries, they are more commonly associated with aerial assaults rather than ground forces. High altitude bombing largely relies on air power, whereas electronic warfare involves disrupting electronics and communications, which are generally more tactical and may not directly involve ground troops. Unmanned aerial vehicles, although they may be employed by ground forces, are not representative of ground force actions in themselves. Hence, the most pertinent embodiment of a threat from ground forces is the direct launching of mortars or rockets at friendly compounds.