Final answer:
When adjusting the driver's seat for best driving posture, the body should be about a forearm's length away from the steering wheel.
Step-by-step explanation:
When adjusting the driver's seat for best driving posture, it is important to set the seat in an upright position where your body is about a forearm's length away from the steering wheel. This allows for a comfortable distance that promotes proper arm extension and reduces strain on the back and neck. Sitting too close to the steering wheel can limit movement and increase the risk of injury in case of a collision, while sitting too far away can require excessive reaching and negatively impact control of the vehicle. Therefore, maintaining the correct distance from the steering wheel is crucial for optimal driving posture.