What color of smoke signal indicates distress?

The correct answer is red, as a red smoke signal universally signifies distress or an emergency situation. In various sectors, including search and rescue operations, the use of red smoke is a recognized distress signal that alerts others to the fact that immediate assistance is required. This color is chosen because it stands out in various environments, making it easier to detect from a distance or against backgrounds such as foliage or bodies of water.

In maritime settings, military operations, and other emergency protocols, red smoke is specifically used to convey an urgent need for help. This established meaning makes red the most effective choice among the options provided, as it communicates a clear and immediate message to nearby personnel or rescuers.