Final answer:
The precise minimum distance cranes must maintain from power lines is not provided in the information given and it's important to consult the latest OSHA guidelines or local regulations for accurate safety distances.
Step-by-step explanation:
When operating cranes near power lines, it is crucial for safety to maintain a sufficient distance to prevent electrical hazards. The specific distance that cranes must maintain from power lines is not provided within the information given; therefore, I cannot confidently provide the correct answer among the options given. It is essential to refer to the latest Occupational Safety and Health Administration (OSHA) guidelines or other local regulations for the precise requirements as they can often vary based on the voltage of the power lines and other factors.