Which of the following should not be worn while operating heavy machinery?

The choice regarding loose clothing is the correct answer because wearing such attire can pose significant safety hazards while operating heavy machinery. Loose clothing may easily become caught in moving parts of the machinery, which can lead to severe accidents or injuries. Proper safety practices emphasize the importance of wearing fitted clothing that does not pose a risk of entanglement.

In contrast, tying long hair back is a standard safety measure to prevent it from getting caught in machinery. Closed-toe shoes are necessary to protect the feet from heavy items or equipment, while safety gloves, when appropriate, can protect the hands from cuts or abrasions without risking entanglement. Each of these options supports safety in operation, making loose clothing the only choice that should be avoided.