Hydra is immortal, because

Options

A. Old cells are replaced by new cells
B. Cell do not grow old
C. Of regeneration
D. It never dies.

Answer

**Step-by-Step Solution:**

1. **Understanding the Concept of Immortality in Hydra:**
- The question asks why Hydra is considered immortal. Immortality in this context refers to the organism's ability to avoid death through natural aging processes.

2. **Analyzing the Options:**
- The options provided are:
1. Old cells are replaced by new cells.
2. Cells do not grow old.
3. Of regeneration.
4. It never dies.
- Each option needs to be evaluated to determine which one best explains Hydra's immortality.

3. **Evaluating Each Option:**
- **Option 1:** Old cells are replaced by new cells.
- While this is true for many organisms, it does not specifically explain Hydra's unique ability to avoid death.
- **Option 2:** Cells do not grow old.
- This statement is misleading. Cells do age, but Hydra has mechanisms to counteract aging.
- **Option 3:** Of regeneration.
- Hydra has a remarkable ability to regenerate lost body parts, which contributes to its immortality. This regeneration allows it to replace damaged or lost cells and tissues.
- **Option 4:** It never dies.
- This is an oversimplification; Hydra can die from external factors but has mechanisms that allow it to live indefinitely under ideal conditions.

4. **Conclusion:**
- The most appropriate explanation for Hydra's immortality is its capacity for regeneration. This ability allows Hydra to continuously renew its cells and tissues, effectively preventing aging and death in a natural sense.

5. **Final Answer:**
- Therefore, the correct answer is **Option 3: Of regeneration.**

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