Question

what are the colors of the warning signs that indicate hazards ahead, such as curves in the road or narrow bridges? black letters or symbols on a white background. black letters or symbols on a yellow background. white letters or symbols on a blue background. white letters or symbols on a green background.

Explanation:

Warning signs that indicate hazards ahead, such as curves in the road or narrow bridges, are designed to be highly visible. Yellow is a color that stands out well and catches attention. Black letters or symbols on a yellow background provide a strong contrast, ensuring that drivers can quickly notice and understand the warning.

Answer:

Black letters or symbols on a yellow background.