A lighted red arrow means:

A lighted red arrow means that you may not proceed in the direction indicated by the arrow. This traffic signal specifically indicates a prohibition against movement in that direction, and it is meant to ensure the safety of all road users by reinforcing the requirement to stop.

When you encounter a red arrow, it functions similarly to a standard red traffic light, signaling that you must come to a full stop and cannot continue in the direction the arrow points. This allows for safe crossings of pedestrians or vehicles coming from other directions, thus preventing potential accidents.

In contrast, other choices suggest various allowances for movement that contradict the meaning of a red arrow. Proceeding with caution in the direction of a red arrow would be unsafe and violate traffic rules. The mention of emergency vehicles also does not apply here, as the lighted red arrow is a clear restriction for all vehicles. Lastly, while stopping completely is always essential at a red light, the context of this specific signal is that no movement is permitted at all in the direction indicated.