The only personnel allowed to have their body parts outside of the suspended personnel platform during hoisting and lowering operations are:

The correct choice indicates that signal persons are the only personnel permitted to have their body parts outside of the suspended personnel platform during hoisting and lowering operations. This is due to the specific role that signal persons play in ensuring safety and communication during these processes. They are responsible for directing the operation from a place where they can maintain clear visibility and provide necessary signals, while the other personnel on the platform must remain safely within its confines to minimize the risk of injury.

In contrast, master riggers, qualified persons, and craft workers are generally expected to adhere to strict safety protocols that require them to keep all parts of their body within the platform. This helps to protect them from potential hazards associated with the lifting operation, including falling objects or accidental movements of the platform. Their roles usually involve overseeing or performing tasks where visibility or mobility outside of the platform can be restricted for their safety.