Controlling your body posture means you should:

Controlling your body posture is crucial in security situations as it directly affects how others perceive your demeanor and intentions. Avoiding sudden movements is essential because abrupt actions can be perceived as aggressive or threatening, which may escalate a situation unnecessarily. Maintaining a calm and composed posture helps establish a sense of control and confidence, making interactions smoother and potentially defusing tension.

The other options do not align as well with the principles of maintaining an effective and non-threatening body posture. For example, maintaining physical contact, such as a hand on the person's shoulder, can invade personal space and may be uncomfortable or interpreted as aggressive. Maintaining eye contact is important but should be balanced; prolonged eye contact can come off as confrontational. Similarly, staying within three feet of someone may violate personal space and make them feel encroached upon, which is counterproductive in many situations. Therefore, the emphasis on avoiding sudden movements serves to enhance your overall body language and approach in engaging with others in a professional capacity.