Which of the following is a sign of pre-attack posture?

The boxer stance is indicative of a pre-attack posture because it typically involves positioning the body in a way that facilitates both defense and offensive movements. This stance often includes a slight bend in the knees, hands positioned near the face, and feet shoulder-width apart, which allows for quick engagement when aggression is necessary. Such a stance is instinctual for individuals who may be preparing to confront or respond to a perceived threat.

In contrast, other options present characteristics that do not necessarily indicate a readiness to attack. An open stance generally signals openness and non-aggressiveness, creating an inviting demeanor rather than one poised for aggression. An aggressive tone might communicate intimidation but does not reflect physical readiness for an attack. Similarly, relaxed hands suggest calmness and lack of hostility, which would not align with a pre-attack posture. Thus, the boxer stance is uniquely identified with physical and mental preparation for a potential confrontation, making it the correct answer.