Final answer:
The minimum distance that a crane should stay from power lines is Option 4: 20 feet.
Step-by-step explanation:
The minimum distance that a crane should stay from power lines is Option 4: 20 feet. This is important for safety reasons, as power lines carry high voltage electricity and can pose a serious risk if they come into contact with equipment like cranes. By maintaining a distance of 20 feet, the risk of accidental contact and potential electrocution is minimized.