Ichthyosaurs are

Options

A. Large marine reptiles which are presently found in oceans
B. Large marine reptiles which are extinct
C. Large marine fishes which are presently found in oceans
D. Large marine fishes which are extinct

Answer

**Step-by-Step Solution:**

1. **Understanding Ichthyosaurs**: Ichthyosaurs were a group of marine reptiles that existed during the time of the dinosaurs. They are not fish but are classified as reptiles.

2. **Physical Characteristics**: Ichthyosaurs had a large body structure, similar to modern-day whales or sharks. Their body shape was streamlined, which is typical for marine animals.

3. **Habitat**: Ichthyosaurs were exclusively marine creatures, meaning they lived in the ocean and were adapted to a life in water.

4. **Extinction**: It is important to note that Ichthyosaurs are extinct. They lived during the Mesozoic Era and are not found in present-day oceans.

5. **Correct Option**: Based on the above points, the correct option is that Ichthyosaurs are large marine reptiles that are extinct. The other options incorrectly suggest that they are currently found in the ocean or classify them as fish.

**Final Answer**: Ichthyosaurs are large marine reptiles that are extinct.

---