Final answer:
The correct option is 3. Crane operators must maintain continuous communication with riggers for safety during lifting operations. Continuous communication is crucial to prevent accidents and keep updates flowing between the operator and the rigger.
Step-by-step explanation:
Crane operators must be in constant, clear, and continuous communication with the rigger to ensure safety and efficiency in lifting operations. While all these types of communication are important when it comes to the critical nature of the communication required between a crane operator and a rigger, the most suitable option is 3) continuous.
Continuous communication ensures that the operator is always updated with the latest information regarding the load, the conditions, and the signals from the rigger. This can prevent accidents and ensure a safe work environment. Therefore, it is imperative that the communication does not break down at any point during the lifting process.