Which of the following is not a part of the human respiratory system?

Options

A. lungs
B. oesophagus
C. trachea
D. diaphragm

Answer

**Step-by-Step Solution:**

1. **Identify the Components of the Human Respiratory System:**
- The human respiratory system includes organs such as the lungs, trachea, and diaphragm. These organs are involved in the process of breathing and gas exchange.

2. **Analyze the Options Given:**
- The question asks which option is NOT a part of the human respiratory system. The options typically include:
- Lungs
- Esophagus
- Trachea
- Diaphragm

3. **Evaluate Each Option:**
- **Lungs:** These are the main organs for respiration where oxygen is absorbed and carbon dioxide is expelled.
- **Esophagus:** This is the food pipe that carries food from the mouth to the stomach. It is not involved in respiration.
- **Trachea:** This is the windpipe that connects the throat to the lungs and is essential for air passage.
- **Diaphragm:** This is a muscle that aids in the process of breathing by contracting and relaxing to help draw air into the lungs.

4. **Determine the Correct Answer:**
- Since the esophagus is responsible for transporting food and does not play a role in respiration, it is the correct answer to the question.

5. **Conclusion:**
- The part that is NOT a part of the human respiratory system is the **esophagus**.

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