What type of sign warns drivers to watch for cross traffic?

The correct answer is the sign that indicates "Crossroad ahead." This type of sign is specifically designed to alert drivers that they are approaching an intersection where cross traffic may be present. Such warning signs are essential for enhancing safety, as they prepare drivers to be vigilant for vehicles that may intersect their path.

While yield and stop signs indicate rules for vehicles already at an intersection, they do not specifically warn drivers about the possibility of approaching cross traffic. A merge sign indicates that a lane will be merging, but it does not inform drivers about potential cross traffic. Therefore, the "Crossroad ahead" sign is the most appropriate choice for alerting drivers to watch for vehicles from side roads or intersections, ultimately promoting safer driving practices.