Which one of the following animals has two separate circulatory pathways?

Options

A. Shark
B. Frog
C. Lizard
D. Whale

Answer

To determine which of the following animals has two separate circulatory pathways, we need to analyze the circulatory systems of each option provided: shark, frog, lizard, and whale.

### Step-by-Step Solution:

1. **Understand the Concept of Circulatory Pathways**:
- Animals can have different types of circulatory systems: single circulation and double circulation.
- In double circulation, blood passes through the heart twice: once for pulmonary circulation (heart to lungs) and once for systemic circulation (heart to the rest of the body).

2. **Analyze Each Option**:
- **Shark**: Sharks have a single circulatory system where blood flows through the heart once. They have a two-chambered heart and do not have separate pulmonary and systemic circuits.
- **Frog**: Frogs have a three-chambered heart and exhibit a form of double circulation, but it is not completely separate as in mammals. They have some mixing of oxygenated and deoxygenated blood.
- **Lizard**: Lizards also have a three-chambered heart and a similar circulatory system to frogs, which does not fully separate the two circulatory pathways.
- **Whale**: Whales are mammals and possess a four-chambered heart, which allows for a complete separation of oxygenated and deoxygenated blood. They have a true double circulatory system with distinct pulmonary and systemic circuits.

3. **Conclusion**:
- Among the given options, the whale is the only animal that has two separate circulatory pathways, making it the correct answer.

### Final Answer:
**Whale**