Occurrence of endemic species in Sourth America and Australia is due to

Options

A. These species has been extinct from other regions
B. Continental separation
C. There is no terrestrial route to these places
D. Retrogressive evolution.

Answer

### Step-by-Step Solution:

1. **Understanding Endemic Species**:
- Endemic species are those species that are native to a specific geographical area and are not naturally found elsewhere.

2. **Geographical Context**:
- The question specifically mentions South America and Australia, both of which have unique flora and fauna that are not found in other parts of the world.

3. **Continental Separation**:
- The primary reason for the occurrence of endemic species in these regions is continental separation. This refers to the process by which continents drift apart over geological time, leading to isolation of species.

4. **Continental Drift**:
- Continental drift is the scientific theory that explains how continents move across the Earth's surface. This movement can lead to the separation of species, allowing them to evolve independently in isolated environments.

5. **Incorrect Options**:
- The other options mentioned (extinction from other regions, retrogressive evolution) do not adequately explain the presence of endemic species. Extinction refers to species that no longer exist, and retrogressive evolution describes a process where complex forms evolve into simpler forms, which is not relevant to the occurrence of endemic species.

6. **Conclusion**:
- Therefore, the occurrence of endemic species in South America and Australia is primarily due to continental separation caused by continental drift.

### Final Answer:
The occurrence of endemic species in South America and Australia is due to **continental separation**.

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