Under what condition may the attendant leave the opening of the confined space?

The correct answer emphasizes the critical role of the attendant in ensuring the safety of workers within a confined space. An attendant is responsible for monitoring workers inside the space and maintaining communication with them, as well as being ready to initiate rescue operations if necessary. The presence of an attendant is essential for providing a quick response to emergencies or changes in conditions.

The requirement for an attendant to only leave the opening of the confined space when relieved by another attendant highlights the importance of continuous oversight. If the attendant leaves without proper replacement, no one is watching over the safety of the workers inside, which can put them at risk should an emergency occur.

Therefore, maintaining a constant presence at the confined space opening is crucial for the overall safety of the operation. This response aligns with OSHA guidelines, which are designed to protect workers by ensuring that trained personnel are always available to handle any potential hazards that may arise.