What does a yellow diamond-shaped sign indicate?

A yellow diamond-shaped sign is specifically designed to alert drivers to potential hazards or changes in conditions on the road ahead. This type of sign is crucial for safety as it serves as a warning to motorcyclists and other drivers to be vigilant and prepared for possible obstacles, such as curves, intersections, or pedestrian crossings.

The yellow color signifies caution and is universally recognized in traffic signage. Moreover, the diamond shape is distinct from other traffic signs, making it immediately noticeable. By preparing drivers for possible hazards, these signs help reduce the risk of accidents and promote safer driving behaviors.

The other options refer to specific traffic conditions that are not indicated by a yellow diamond sign. For instance, speed limit changes are typically shown with rectangular signs, road closures may be indicated with specific messages or signs in a different format, and direction changes are indicated by arrows or other specific signs. Therefore, the yellow diamond sign's primary function is to warn of potential hazards ahead, solidifying answer B as the correct choice.