Trail lines, basket slings, or hoisting cables should never be what during an operation?

During an operation, it is crucial that trail lines, basket slings, or hoisting cables be securely attached to the boat. This ensures that all equipment necessary for the operation is properly accounted for and functional, minimizing the risk of accidents or equipment loss. If these items are not attached, it could jeopardize the safety of the operation, prevent effective rescue or cargo handling, and could lead to a failure in operational readiness.

The other choices do not capture the essence of operational safety and integrity. For example, while disconnected lines or cables could lead to complications, the core issue is the importance of maintaining secure attachment during operations. Unused equipment might not pose an immediate risk, but it indicates a lack of preparedness. Tangled lines could create operational hazards, but the primary focus in this context is ensuring that all lines and cables are properly secured to the boat.