Longest cells in the human body are:

Options

A. leg muscle cells
B. bone cells
C. nerve cells
D. heart muscle cells

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the longest cells in the human body. We need to evaluate different types of cells to determine which one is the longest.

2. **Evaluating the Options**:
- **Leg Muscle Cells**: These are skeletal muscle cells, which can be approximately 2-3 cm in length.
- **Bone Cells**: Bone cells are relatively small, measuring about 7 micrometers in depth and around 15 micrometers in length.
- **Nerve Cells**: Nerve cells, or neurons, can be very long, with some extending up to 1 meter in length.
- **Heart Muscle Cells**: Heart muscle cells (cardiomyocytes) are about 100-150 micrometers in length.

3. **Comparing the Lengths**:
- Leg muscle cells: 2-3 cm (20-30 mm)
- Bone cells: 15 micrometers
- Nerve cells: Up to 1 meter (1000 mm)
- Heart muscle cells: 100-150 micrometers

4. **Conclusion**: Among all the options, nerve cells are the longest, with some reaching lengths of up to 1 meter. Therefore, the correct answer is nerve cells.

**Final Answer**: The longest cells in the human body are nerve cells.

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