If a worker bends from the waist instead of bending knees while lifting, which risk increases?

Correct answer: Back strain

The direct answer is A: Back strain. Ergonomics means fitting the task, tools and body position so that work is safer and easier. While lifting, bending the knees allows the strong leg muscles to help and keeps the load nearer to the body. Bending mainly from the waist makes the lower-back muscles and spinal joints carry more force. Step by step: the worker bends the trunk, the load is often farther from the body, the back acts like a lever, and strain on the back increases. Option A is correct because this posture can cause back strain, pain or injury, especially when repeated or when the object is heavy. Option B, eye comfort, concerns the eyes and is not the main risk in lifting posture. Option C, less noise, has no logical connection with bending technique. Option D, better balance, is wrong because knee bending usually supports safer balance; waist bending can make control poorer. Memory cue: bend knees, keep the back straighter, hold the load close, and lift with the legs.