On a vertical signal face using only circular lights, what is the order from top to bottom?

Correct answer: A. – Red, yellow, green
Iowa law places the circular red indication above circular yellow and circular green on a vertical traffic-signal face. Accordingly, a standard three-light vertical signal is arranged red, yellow, then green from top to bottom. Horizontal signal faces place red toward the left.
Source: Iowa Code § 321.258 — Arrangement of lights on official traffic-control signals




