What is the correct ergonomic posture for a driver to prevent back strain during long hours of driving?

1. Sit upright with the back fully supported by the backrest, shoulders relaxed, and hips close to the back of the seat
2. Slouch forward over the steering wheel to improve forward visibility
3. Recline the seat back as far as possible to drive in a semi-lying position
4. Keep the steering wheel as high as possible to stretch the arms