4-chambered heart is in

Options

A. All reptiles
B. All birds + crocodile + all mammals
C. Only Mammals
D. Frog

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which group of animals possesses a 4-chambered heart.

2. **Evaluating the First Option - All Reptiles**:
- Reptiles generally have a 3-chambered heart, which consists of two atria and one ventricle.
- Therefore, this option is incorrect.

3. **Evaluating the Second Option - All Birds, Crocodiles, and All Mammals**:
- Birds and mammals both have a 4-chambered heart, which consists of two atria and two ventricles.
- Crocodiles, although reptiles, also possess a 4-chambered heart, making this option correct.
- Hence, this option is correct.

4. **Evaluating the Third Option - Only Mammals**:
- While mammals do have a 4-chambered heart, this option is incomplete because it excludes birds and crocodiles, which also have a 4-chambered heart.
- Therefore, this option is incorrect.

5. **Evaluating the Fourth Option - Frog**:
- Frogs have a 3-chambered heart, consisting of two atria and one ventricle.
- Thus, this option is incorrect.

6. **Conclusion**: The correct answer is the second option, which includes all birds, crocodiles, and all mammals, as they all possess a 4-chambered heart.

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