To maintain proper body alignment and posture, you must: [1] Bend at the hips and lift using your back muscles for support. [2] Increase balance by bringing the center of gravity closer to the base of support. [3] Ensure the bed is at its lowest position to reduce the risk of falls.[4] Widen the base of support by spacing your feet comfortably apart.

To maintain proper body alignment and posture while lifting something or performing a task, it’s important to follow certain guidelines. However, your first point regarding bending at the hips and using your back muscles for support is incorrect and could lead to injury. Here's the proper method:

1. Do not bend at the hips and lift using your back muscles for support. Instead, you should bend at the knees and hips, keeping your back straight, and lift with your leg muscles. This protects your back by distributing the weight more evenly through your stronger leg and core muscles.

2. Increase balance by bringing the center of gravity closer to the base of support is correct. When lifting, you should hold the object as close to your body as possible. This reduces the strain on your body and helps to maintain balance.

3. Ensuring the bed, or any work surface, is at the right height is indeed important, but the lowest position is not always the best. You should adjust the height of the bed or work surface so that you do not have to bend forward excessively. This means that sometimes raising the surface will be safer to prevent stooping, which can cause back strain.

4. Widening the base of support by spacing your feet comfortably apart is also correct. A wider stance provides a more stable base and reduces the risk of losing your balance. Your feet should typically be shoulder-width apart when lifting.

Extra: It's very important to maintain proper body mechanics to prevent injuries during activities that involve lifting, reaching, or bending. The back, especially the lower back, can be quite vulnerable to injury if not taken care of through proper techniques. One common injury is muscle strain or worse, damage to spinal discs, which can occur from improper lifting techniques.

Center of gravity refers to the point in a body or system where the weight is evenly distributed and if it's kept low and close to your body, it helps you stay stable.

Base of support means the contact area beneath you, usually your feet, that bears your body weight. When this base is widened, your stance becomes more stable, as your weight is distributed over a larger area, and this helps prevent falls or instability while moving or lifting objects.

Lastly, ensuring that the work surface, like a bed in healthcare settings, is at the appropriate height reduces risk by decreasing the need to bend or reach too far, which can put undue stress on the muscles and spine. Adjusting the height of the bed or work surface allows the person performing the task to work in a "neutral" body position, which is the safest and most ergonomically correct position to reduce strain and the potential for injury.