Rete mirabile is found in

Options

A. Cartilaginous fishes
B. Bony fishes
C. Aquatic mammals
D. Both B and C.

Answer

### Step-by-Step Solution:

1. **Understanding Rete Mirabile**:
- Rete mirabile is a network of blood vessels, specifically a complex of arteries and veins that are closely associated with each other.

2. **Identifying Where Rete Mirabile is Found**:
- Rete mirabile is present in certain vertebrates.
- The options provided are:
- A) Cartilaginous fishes
- B) Bony fishes
- C) Aquatic mammals
- D) Both B and C

3. **Analyzing Each Option**:
- **Cartilaginous Fishes**: These include sharks and rays, which do not possess a rete mirabile.
- **Bony Fishes**: Many bony fishes have a rete mirabile that helps in buoyancy by filling the swim bladder with oxygen.
- **Aquatic Mammals**: Some aquatic mammals also have a rete mirabile that aids in oxygen supply and buoyancy.
- **Both B and C**: This option combines the presence of rete mirabile in both bony fishes and aquatic mammals.

4. **Conclusion**:
- Since rete mirabile is found in both bony fishes and aquatic mammals, the correct answer is **D) Both B and C**.

### Final Answer:
Rete mirabile is found in **both bony fishes and aquatic mammals** (Option D).