Final answer:
The correct answer is option A. Lift with straight back and use legs.
Step-by-step explanation:
The best way to prevent back and leg strains is to lift with a straight back and use your legs to power the lift. When an individual bends down to lift an object and keeps their back straight, they are using their legs—specifically the strong muscles of the thighs and buttocks—to lift, which is the proper lifting technique. This method significantly reduces the force exerted on the spine, making it about 5.6 times smaller compared to when a person lifts with their back. It is essential to maintain good posture while lifting, so the person's center of gravity remains aligned and minimizes strain on the back muscles and spine.
It is also important to stand or sit with good posture, where the center of gravity is directly above the pivot point in the hips. This position helps to avoid back strain and potential damage to discs. Furthermore, muscular balance is crucial when carrying loads, as demonstrated by individuals who adjust their posture to maintain their center of gravity over their base of support—similar principles apply to lifting objects safely.