A red signal light with a green arrow showing indicates what?

Answer: B — Drivers may proceed with caution in the direction of the arrow.

A red signal light accompanied by a green arrow indicates that while the overall signal is red, there is a specific permission for drivers to proceed in the direction of the green arrow. The green arrow provides a protected turn, meaning drivers are allowed to move in that direction while oncoming traffic and pedestrians are effectively controlled by the red light. In this situation, it's important to understand that the red signal still applies to other directions of traffic; however, the green arrow grants a right of way for turning. Drivers must still exercise caution, ensuring that the intersection is clear and that it is safe to proceed in the direction indicated by the green arrow. It effectively directs traffic flow in a safe manner, minimizing conflicts with other traffic and pedestrians. In contrast, other answer choices reference stopping or waiting indefinitely at the red light, which does not account for the specific instruction provided by the green arrow, and consequently do not capture the correct application of traffic signals in this scenario.