What signal is used to interrupt or cease firing?

The correct choice regarding the signal used to interrupt or cease firing is the first option, where the leader raises his arm and hand palm outward in front of his forehead and brings it downward sharply. This specific signal is universally recognized in military training as a clear and decisive way to communicate the command to stop firing.

The upward position of the arm with the palm outward indicates the need for immediate attention from all personnel and conveys the urgency of the situation. The downward motion further reinforces the message, making it visually engaging and hard to miss among the noises of a combat environment. This method is critical for ensuring that all members of the unit understand the command, especially in high-stress scenarios where verbal communication may be hampered.

In contrast, while shouting "halt" (the second option) or using a whistle and hand gestures (the third option) could serve as communication methods, they might not provide the same level of clarity or immediate recognition in the chaotic nature of firing situations. Similarly, lowering a weapon and waving it side to side (the fourth option) does not convey a definitive ceasing action; it can easily be misinterpreted or missed, making it less effective as a signal for stopping fire.