Which of the following systems undergoes maximum changes in frog during metamorphosis?

Options

A. Digestive system
B. Circulatory system
C. Reproductive system
D. Nervous system

Answer

To determine which system undergoes the maximum changes in frogs during metamorphosis, we can analyze the options provided and understand the metamorphic process of frogs.

### Step-by-Step Solution:

1. **Understanding Metamorphosis**:
- Metamorphosis is a biological process where an organism undergoes significant physical changes during its development. In frogs, this process transforms a tadpole (larval stage) into an adult frog.

2. **Identifying the Systems**:
- The question provides four systems to consider:
- Digestive system
- Circulatory system
- Reproductive system
- Nervous system

3. **Analyzing the Tadpole Stage**:
- In the tadpole stage, frogs have gills for respiration as they live in aquatic environments. Their body structure is adapted for swimming.

4. **Changes During Metamorphosis**:
- As frogs undergo metamorphosis, they transition from having gills to developing lungs. This is a significant change since adult frogs are capable of living both in water and on land.

5. **Evaluating Each System**:
- **Digestive System**: While there are some changes, they are not as drastic as in the respiratory system.
- **Circulatory System**: The circulatory system also undergoes changes, particularly in the heart structure, but the most notable changes are in respiration.
- **Reproductive System**: This system develops as the frog matures, but it does not undergo immediate changes during metamorphosis.
- **Nervous System**: There are some changes, but they are not as pronounced as those in the respiratory system.

6. **Conclusion**:
- The system that undergoes the maximum changes during the metamorphosis of a frog is the **Circulatory System**, primarily due to the transition from gills to lungs.

### Final Answer:
The system that undergoes maximum changes in frogs during metamorphosis is the **Circulatory System**.