Openings in the floor or wall where a worker can fall to a lower level of four feet or greater must be protected by a hard barricade, such as a guardrail or cover. When workers must work inside the hard barricade, what must the workers do?

A. Install caution tape to warn other employees of the fall hazard

B. Place bright-colored cones 6 feet from the opening

C. Utilize a personal fall restraint or fall arrest system

D. Inform all employees to watch out for fall hazards

E. Nothing, fall hazards less than 6 feet do not require fall protection