Which signal is used to get the attention of a person or group during a patrol?

Waving one arm above the head is an effective method for gaining the attention of a person or group during a patrol because it is both visible from a distance and easily recognizable as a signal for attention. This motion creates a clear visual cue that can stand out in various environments, making it suitable for varied patrol scenarios where quick visibility is essential.

In the context of patrol operations, where stealth and communication are critical, using a signal that can be easily seen without producing excessive noise is essential. Waving an arm does not require verbal communication, which might alert adversaries or disrupt the careful nature of a patrol. This option aligns with the communication tactics that are employed in military operations, emphasizing the importance of non-verbal signals for maintaining situational awareness and ensuring safety.