What indicates a mandatory action in traffic signs?

The choice indicating a mandatory action in traffic signs is associated with white and black signs. These signs typically convey regulatory information that drivers are required to follow. For instance, signs that display limits on speed, lane usage, or instructions to yield or stop are often white with black lettering or symbols. This color combination is standardized to ensure clarity and compliance among drivers, making it easily recognizable as an authoritative directive.

In contrast, other colors on signs convey different meanings: yellow signs are usually warnings about potential hazards; red signs indicate prohibitions, such as stopping or yielding; and green signs provide informational messages, often related to directions or guidance. Each color serves a specific purpose, but the white and black signs universally communicate actions that must be adhered to on the road.