Which out of the following options is not true regarding movement in a fish?

Options

A. Muscles that help the fish to move are present on either side of the backbone.
B. The sweeping of the tail is due to the contraction and relaxation of muscles.
C. The fins present on the sides of the body do not play any role in the movement.
D. Streamlined body shape of fish helps its movement in water.

Explanation

To determine which statement is not true regarding movement in a fish, we can analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Fish Movement**: Fish move primarily through the contraction and relaxation of muscles located on either side of their backbone. This creates a wavy motion that propels them forward.

2. **Analyzing Muscle Function**: The muscles on either side of the backbone are indeed responsible for the movement of the fish. This statement is true.

3. **Tail Movement**: The sweeping of the tail is also due to the contraction and relaxation of muscles. This movement is crucial for propulsion and steering. This statement is true.

4. **Role of Fins**: The statement that fins do not play any role in movement is incorrect. Fins are essential for providing stability, direction, and balance while swimming. Therefore, this statement is false.

5. **Streamlined Body Shape**: The streamlined shape of a fish helps it to move efficiently through water by reducing drag. This statement is true.

6. **Conclusion**: Since the statement about fins not playing a role in movement is false, we conclude that this is the option that is not true regarding movement in a fish.

### Final Answer:
The statement that is not true regarding movement in a fish is: "The fins present on the sides of the body do not play any role in movement."

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