What is a critical requirement for the condition of electric and air lines?

The critical requirement for the condition of electric and air lines is that there should be no cuts and nothing broken. This is essential because any damage to the electric or air lines can lead to serious safety hazards. For instance, cuts or breaks in these lines can result in loss of air pressure, which is crucial for braking systems, or disrupt electrical connections that power essential lighting and signaling systems. Ensuring that the lines are intact guarantees that the vehicle operates safely and effectively, reducing the risk of accidents caused by component failure.

While other options may seem relevant, they don’t address the fundamental safety aspect required for these lines. Proper connections and visibility can be important, but the overarching concern is that any damage such as cuts would compromise the vehicle's functionality and safety, making the integrity of the lines paramount.