Which of the following is the structural and functional unit of the excretory system?

Options

A. Neuron
B. Nephron
C. Alveolus
D. Both (A) and (B)

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the structural and functional unit of the excretory system. We need to identify which option corresponds to this definition.

2. **Analyzing the Options**:
- **Option 1: Neuron**: This is a nerve cell and is part of the nervous system, not the excretory system. Therefore, this option is incorrect.
- **Option 2: Nephron**: The nephron is known as the structural and functional unit of the excretory system. It plays a crucial role in filtering blood and forming urine, thus removing waste products from the body. This option is correct.
- **Option 3: Alveolus**: Alveoli are tiny air sacs in the lungs involved in the respiratory system, not the excretory system. Thus, this option is incorrect.
- **Option 4: Both A and B**: Since both neuron and alveolus are not part of the excretory system, this option is also incorrect.

3. **Conclusion**: After evaluating all the options, the correct answer is **Option 2: Nephron**, as it is the structural and functional unit of the excretory system.

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