Fever is caused by

Options

A. phagocytes
B. pyrogens
C. haptens
D. pus

Answer

To answer the question "Fever is caused by," we will analyze the provided options step by step.

### Step 1: Understand the Options
We have four options to consider:
1. Phagocytes
2. Pyrogens
3. Haptens
4. Pus

### Step 2: Analyze Each Option
- **Phagocytes:** These are a type of white blood cell that engulf and digest pathogens like bacteria. While they play a crucial role in the immune response, they do not directly cause fever.

- **Pyrogens:** These are substances that induce fever. They can be derived from microorganisms (like bacteria) or can be produced by the body in response to infection. Pyrogens act on the hypothalamus to raise the body's temperature, leading to fever.

- **Haptens:** These are small molecules that can bind to antibodies but do not trigger an immune response on their own. They are not related to the cause of fever.

- **Pus:** This is a thick fluid that accumulates at the site of infection, consisting of dead white blood cells, bacteria, and tissue debris. While pus is a sign of infection and inflammation, it is not a direct cause of fever.

### Step 3: Identify the Correct Answer
Based on the analysis, the correct answer is **Pyrogens** because they are specifically known to induce fever.

### Final Answer
Fever is caused by **Pyrogens**.

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