Final answer:
The red lights are generally arranged on the left side when traffic lights are horizontal.
Step-by-step explanation:
The arrangement of the red lights on a traffic light when it is horizontal depends on the country where you are located. However, in many countries, like the United States, the red lights are arranged on the left side when the traffic light is horizontal. The green lights are usually on the right side and the yellow lights in the middle.
For example, in the United States, a horizontal traffic light would typically have the red light on the left, the yellow light in the middle, and the green light on the right.
In summary, the red lights are generally arranged on the left side when traffic lights are horizontal, but this can vary depending on the country.