What is indicated by a diamond-shaped yellow sign with black markings?

Answer: C — warning of hazards ahead

A diamond-shaped yellow sign with black markings is universally recognized as a warning sign, indicating potential hazards ahead. These signs are typically used to alert drivers to changes in road conditions, the presence of pedestrians, curves, road work zones, and other conditions that could affect safety. The yellow color signals caution, while the diamond shape is standard for warning signs, making them easily identifiable to drivers. In contrast, a stop sign is octagonal and has distinct red coloring, which is designed to command immediate attention and prompt a complete stop. A speed limit sign, which is typically rectangular, conveys regulatory information about how fast vehicles can legally travel in a given area. Parking area signs are also usually rectangular and provide specific information about parking regulations rather than warnings. Thus, the diamond-shaped yellow sign stands out as a clear indicator of caution for drivers, providing essential information to navigate safely ahead.