Which of the following is a color used for danger signs and alerts on a map?

The color red is universally recognized as a symbol of danger and urgency, making it the standard choice for alerting individuals to hazardous conditions on maps and signage. This color is easily visible and draws attention, which is critical when conveying important safety information. In various contexts, including military, aviation, and road signage, red signaling has established itself as an effective way to communicate warnings or caution.

In contrast, other colors like black, green, and blue do not convey the same immediacy of danger. Black is often used for text and outlines, while green typically indicates safety or information, and blue is often associated with informational signs or services. Thus, red is distinctly chosen for danger situations to ensure that risks are quickly communicated and recognized by individuals navigating an area.