Which of the following actions contributes to litter discipline?

Maintaining proper litter discipline is crucial for environmental respect and operational effectiveness in a military context. The action of not dropping trash while on patrol directly supports this principle. By ensuring that no litter is left behind, the individual contributes to keeping the operating environment clean, minimizes the risk of compromising the team's position or health, and adheres to the military’s standards of maintaining a responsible footprint in the field. Proper litter discipline not only reflects respect for nature but also enhances unit cohesion and operational security by not leaving behind evidence of the team's presence.

The other choices, while also important in various contexts, do not directly address litter discipline. Responsible use of flashlights pertains to stealth and visibility management, maintaining silence relates to operational security and communication, and providing clear signals is essential for team coordination and operational effectiveness. However, these actions do not explicitly contribute to litter management or environmental responsibility in the same way as refraining from dropping trash.