The major function of swim-bladder in fish is

Explanation

Fish have a special organ called the swim-bladder, which is a gas-filled sac located in their abdomen. One of the major functions of the swim-bladder is to help the fish control its buoyancy in water. Buoyancy is the upward force exerted by water that helps the fish stay afloat and move up or down in the water column. When the fish wants to rise in the water, it inflates its swim-bladder with gas, which makes it less dense than water, allowing it to float upwards. Conversely, when the fish wants to sink, it deflates its swim-bladder, which makes it denser than water, causing it to sink. Therefore, the correct option for the major function of swim-bladder in fish is D: buoyancy. Swim-bladders help fish regulate their buoyancy and maintain their position in the water column. Option A (breathing), B (swimming), C (diving), are not the correct option Understanding the role of swim-bladders in fish is essential for understanding the adaptations that help fish survive in aquatic environments.