Living fossil:-

Options

A. Cycas
B. Ginkgo
C. Psilotum
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding the term "Living Fossil":**
- A living fossil is a term used to describe plants or animals that have remained relatively unchanged over long geological periods and closely resemble their fossilized ancestors.

2. **Identifying examples of living fossils:**
- The question provides several options: Cycus, Ginkgo, Cyrotump, or all of the above. We need to analyze each option to determine if they qualify as living fossils.

3. **Analyzing Cycus:**
- Cycus is a genus of plants that has existed for about 300 million years. It has retained many primitive characteristics and has not changed significantly over this vast period, making it a classic example of a living fossil.

4. **Analyzing Ginkgo:**
- Ginkgo biloba, commonly known as the Ginkgo tree, is another example of a living fossil. It has been around for millions of years and is still found today, often used as an ornamental tree and in herbal medicine.

5. **Analyzing Cyrotump:**
- Cyrotump, while not as widely known, also exhibits primitive features that link it to ancient species. This characteristic qualifies it as a living fossil as well.

6. **Conclusion:**
- Since all three options (Cycus, Ginkgo, and Cyrotump) are considered living fossils, the correct answer to the question is "all of the above."

**Final Answer:**
All of the above (Cycus, Ginkgo, Cyrotump) are considered living fossils.

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