Before performing work requiring PPE, employees must know what PPE is needed, when it is necessary, and how to _______ it properly.

The correct option emphasizes the importance of knowing how to "don" personal protective equipment (PPE) properly before engaging in tasks that require it. "Don" specifically refers to the action of putting on the equipment correctly to ensure that it provides the intended protection. This step is crucial because improper donning can compromise the effectiveness of the PPE and expose workers to potential hazards.

Understanding the correct procedure for donning PPE also includes recognizing the sequence in which items should be worn, checking for proper fit, and ensuring that all components function together as intended. This knowledge minimizes the risk of exposure to health and safety hazards, making it an essential part of any safety training program. Knowing how to wear, handle, and remove PPE is important, but the act of donning is foundational, as it is the first step in ensuring worker safety in hazardous environments.