How can you determine if the trailer is securely attached to a truck?

The correct answer focuses on the necessity of ensuring that the kingpin is locked into the fifth wheel correctly and that there is no excessive space between them. This locking mechanism is crucial for the safe and secure connection between the truck and the trailer. If the kingpin is not properly locked, it could lead to a separation of the trailer from the truck while in motion, resulting in a serious accident.

Ensuring that there is no excessive space is critical, as even a small gap can indicate that the connection is not secure and could lead to failure. It is important to perform a thorough inspection of the coupling mechanism to ensure safety.

The other options do not provide reliable methods for ensuring that the trailer is securely attached. Swaying of the trailer could indicate a loose connection, while relying on visual checks alone may not detect safety issues that require a more tactile inspection. Also, perfect alignment of the trailer and cab is not a singular indicator of a secure attachment, as it is possible for them to be visually aligned but not properly connected.