**Core Concept**
In emergency medicine, triage is a process of sorting patients into categories based on the severity of their injuries or illnesses, to prioritize treatment and allocate resources effectively.

**Why the Correct Answer is Right**
Triage is essential in mass casualty situations, such as natural disasters or terrorist attacks, where medical resources are limited. The goal of triage is to identify patients who are critically injured or ill, and prioritize their treatment to maximize the number of survivors. This process involves assessing patients' vital signs, evaluating the severity of their injuries, and categorizing them into different groups, such as immediate treatment, delayed treatment, and expectant treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** Triage is not typically done for patients with minor injuries or illnesses, as they do not require immediate attention.
**Option B:** Triage is not a diagnostic tool, but rather a way to prioritize treatment and allocate resources.
**Option C:** Triage is not limited to emergency situations, but is also used in non-emergency settings to prioritize patients with complex medical needs.

**Clinical Pearl / High-Yield Fact**
The "ABCDE" method is a widely used triage system, where patients are categorized based on their airway, breathing, circulation, disability, and exposure to hazardous materials.

**Correct Answer: C. Triage is done for patients in emergency situations, particularly in mass casualty scenarios.**