Which one of the following is NOT an indicator that the green light is stale?

A green light considered "stale" refers to the possibility that it may turn yellow soon, indicating that drivers should be prepared to stop. In this context, the indication that traffic is moving smoothly suggests that the green light is functioning normally, which implies that it is not stale. There is no immediate indication that it is about to change, allowing for a straightforward, uninterrupted flow of traffic.

In contrast, the other indicators—such as the flashing crosswalk hand, pedestrians in the intersection, and vehicles stopped at the light—suggest a level of caution. A flashing crosswalk hand often indicates that pedestrians are about to cross, warning drivers to be alert. The presence of pedestrians in the intersection and vehicles stopped at the light both signal an irregular situation, which could lead to the anticipation of a yellow light soon. Thus, recognizing that traffic is moving smoothly as the correct choice highlights an absence of those concerns related to a stale green light.