Final answer:
The icon used for triage activities is a red cross on a white background.
Step-by-step explanation:
The icon that would be used for triage activities is typically a red cross on a white background. This symbol is universally recognized as a symbol for first aid and medical assistance. The red cross represents medical care, while the white background symbolizes purity and neutrality. The icon is simple and easily identifiable, which is essential in emergency situations where quick decisions need to be made.