Question

when is eye protection generally required?
whenever a worker is on a jobsite
only when flying debris may be present
only when grinding or cutting metal

Explanation:

Eye protection is a safety - measure. It is required whenever there is a risk of eye - injury. Flying debris can cause eye - injury, so eye protection is needed when it may be present. Just being on a jobsite doesn't necessarily mean there's an eye - injury risk. Grinding or cutting metal is just one of many activities with eye - injury risks.

Answer:

only when flying debris may be present