Fish change its direction suddenly by :

Options

A. Pectoral fin
B. Pelvic fin
C. Caudal fin
D. All the above

Answer

To solve the question "Fish change its direction suddenly by:", we need to analyze the different types of fins in fish and their functions.

### Step-by-Step Solution:

1. **Identify the Options**: The question provides several options regarding the fins of a fish: Pectoral fin, Pelvic fin, Caudal fin, and an option stating "all of the above."

2. **Evaluate the Pectoral Fin**:
- The pectoral fins are located on the sides of the fish and are primarily used for balancing and steering.
- **Conclusion**: The pectoral fin is not primarily responsible for sudden direction changes.

3. **Evaluate the Pelvic Fin**:
- The pelvic fins are located on the underside of the fish and help in stabilizing the fish and preventing it from rolling side to side.
- **Conclusion**: The pelvic fin does not play a major role in sudden directional changes.

4. **Evaluate the Caudal Fin**:
- The caudal fin, also known as the tail fin, is located at the rear of the fish and is crucial for propulsion and maneuverability.
- **Conclusion**: The caudal fin is the primary fin used by fish to change direction suddenly.

5. **Evaluate the Option "All of the Above"**:
- This option suggests that all fins contribute equally to sudden direction changes, which is incorrect based on the functions of the fins discussed.
- **Conclusion**: This option is also incorrect.

6. **Final Answer**: Based on the analysis, the correct answer to the question is the **caudal fin**, as it is specifically designed for sudden changes in direction.