What action is recommended for safe positioning in terms of body posture while sitting?

Maintaining a straight back while sitting is essential for safe positioning and good posture. A straight back helps to align the spine correctly, minimizing strain on the back muscles and reducing the risk of developing musculoskeletal problems. This posture supports the natural curves of the spine and promotes proper alignment, which can enhance comfort and stability during extended periods of sitting.

Good sitting posture can also improve breathing and circulation, as it allows for better lung expansion and blood flow. By keeping the back straight, the pelvis is supported in a neutral position, which helps in maintaining overall body balance and reducing fatigue.

The other options do not promote safe positioning. Leaning back in the chair can lead to slouching, which places undue stress on the spine. Keeping arms relaxed is part of good posture, but without a straight back, the overall effect on posture is compromised. Crossing legs tightly can create imbalances and pressure in the hips and knees, which can lead to discomfort and long-term issues.