Which of the following is a requirement for deploying a standby diver as a working diver?

Deploying a standby diver as a working diver is contingent upon the decision of the surface crew based on the safety assessment of the current situation. The surface crew is responsible for continuously monitoring the dive operation, assessing risks, and ensuring that conditions are suitable for the diver's safety. Their judgment is vital in determining whether the standby diver can safely transition to a working role, taking into account factors such as equipment functionality, environmental conditions, and the health and status of the working diver.

While factors such as the dive type, depth, and specific job location can influence the decision, they don’t solely determine the deployment of a standby diver. The primary concern is the safety, thus making the decision of the surface crew paramount in this scenario.