Final answer:
Signs indicating areas of public recreation are typically brown, guiding people to locations like national parks and campgrounds. The correct answer is option d.
Step-by-step explanation:
The question revolves around the identification of the color used for signs that indicate areas of public recreation. According to the conventions used for traffic and information signage, the color brown is the one typically used for indicating locations of public recreation, such as national parks, campgrounds, and cultural attractions. For example, when you're driving and see a brown sign, it often serves as a guidepost to direct you to recreational sites or historical sites of interest.