Final answer:
The background color of street signs is typically chosen based on visibility and symbolism, with green for directions, red for prohibitions, yellow for warnings, and blue for information.
Step-by-step explanation:
The background color of street signs varies depending on their purpose. The colors of street signs are carefully chosen based on how visible and attention-grabbing they are, as well as what they symbolize. Green is often used for signs that provide directional information such as highway and street names. Red is commonly used for stop signs, yield signs, and other signs indicating prohibitions or commands. Yellow is frequently used for warning signs that alert drivers to potential hazards or changes in road conditions. Lastly, blue is often associated with informational signs about services or facilities such as rest areas and hospitals.