Tetanus disease is caused by

Options

A. Bacterium
B. Virus
C. Fungus
D. Mycoplasma.

Answer

**Step-by-Step Solution:**

1. **Understanding Tetanus**: Tetanus is a serious infection that affects the nervous system and causes muscle stiffness, particularly in the jaw, which is why it is often referred to as "lockjaw."

2. **Identifying the Causative Agent**: The disease is specifically caused by a bacterium. The key bacterium responsible for tetanus is known as *Clostridium tetani*.

3. **Effects of the Bacterium**: *Clostridium tetani* produces a potent toxin that affects the brain and nervous system, leading to muscle stiffness and spasms.

4. **Analyzing the Options**: The options provided are:
- Bacterium
- Virus
- Fungus
- Mycoplasma

5. **Eliminating Incorrect Options**:
- **Virus**: Tetanus is not caused by a virus, so this option is incorrect.
- **Fungus**: Tetanus is not a fungal disease, so this option is also incorrect.
- **Mycoplasma**: This type of microorganism does not cause tetanus, making this option incorrect as well.

6. **Conclusion**: The only correct option is the first one, which states that tetanus disease is caused by a bacterium, specifically *Clostridium tetani*.

**Final Answer**: Tetanus disease is caused by a bacterium (*Clostridium tetani*).

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