Major problems faced by freshwater animals is

Options

A. Gain of salts and loss of water
B. Loss of salts and gain of water
C. Gain of salts and water
D. Loss of salts and water

Answer

### Step-by-Step Solution:

1. **Understanding Freshwater Environments**: Freshwater animals live in environments such as rivers, lakes, and ponds where the concentration of salts (salinity) is very low compared to marine environments (oceans and seas).

2. **Osmoregulation in Freshwater Animals**: Freshwater animals have adapted to their low-salinity environment through a process called osmoregulation. This is the regulation of water and salt concentrations in their bodies.

3. **Problem of Water Gain**: Since freshwater has a lower concentration of salts than the body fluids of freshwater animals, these animals tend to gain water through osmosis. Osmosis is the movement of water from an area of low solute concentration (freshwater) to an area of high solute concentration (inside the animal's body).

4. **Problem of Salt Loss**: As freshwater animals gain water, they also lose salts (ions) from their bodies into the surrounding water, which has a lower concentration of salts. This loss of salts can lead to a condition known as hyponatremia, where the body’s salt levels become too low.

5. **Conclusion**: The major problems faced by freshwater animals are the loss of salts and the gain of water. This is a constant challenge that these animals must manage to maintain homeostasis.

### Final Answer:
The major problems faced by freshwater animals are **loss of salts and gain of water**.

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