Which of the following statement is true about water hyacinth ?

Options

A. It is very useful for farmer because it acts as manure
B. It is found only in sea water
C. It takes oxygen from water which causes death of fishes
D. It gives useful products to be used in medicine

Answer

**Step-by-Step Solution:**

1. **Identify the Plant**: The question asks about water hyacinth, scientifically known as *Eichhornia*.

2. **Understand its Nature**: Water hyacinth is a perennial aquatic plant that grows in water bodies. It rises above the water surface.

3. **Impact on Sunlight Penetration**: As water hyacinth grows, it covers the surface of the water, blocking sunlight from penetrating to the aquatic plants below.

4. **Effect on Aquatic Plants**: The blockage of sunlight prevents other aquatic plants from photosynthesizing, leading to their decline and eventual death.

5. **Accumulation of Organic Matter**: As the aquatic plants die, they decompose and form a thick layer of organic matter on the water surface.

6. **Oxygen Production**: While water hyacinth does produce oxygen, it also consumes oxygen for its own growth. This leads to a decrease in dissolved oxygen levels in the water.

7. **Impact on Aquatic Animals**: The reduction in oxygen levels affects aquatic animals, such as fish, leading to their death due to hypoxia (lack of oxygen).

8. **Conclusion**: The true statement about water hyacinth is that it blocks sunlight, uses oxygen from the water, and contributes to the death of aquatic animals.

**Final Answer**: The correct statement about water hyacinth is that it blocks sunlight and consumes oxygen, leading to the death of aquatic animals.

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