Which principle emphasizes the adaptable nature of direct fire operations based on environmental conditions?

The principle that emphasizes the adaptable nature of direct fire operations based on environmental conditions is accurately captured by planning for extreme limited visibility conditions. This principle recognizes that various environmental factors, such as fog, darkness, or heavy rain, can significantly impact visibility and, consequently, the effectiveness of direct fire operations. By planning for these conditions, military personnel can make proactive adjustments to their strategies and tactics, ensuring that they remain effective even when visibility is compromised. This adaptability is crucial for maintaining operational effectiveness and achieving objectives during adverse conditions.

In contrast, other options focused on aspects like developing contingencies or massing the effects of fire, do not directly address the need for adaptability tied specifically to varying environmental conditions. Instead, they might emphasize overall operational readiness or tactics without honing in on the challenges posed by limited visibility.