Choose the correct Statement.

Options

A. 0.1% of impurities in sewage water also consist of suspended solids like fecal matter , bacteria , paper fibers , etc. .
B. Mauve-coloured flowers are a characteristic feature of the world's most problematic weed .
C. Algal blooms cause deterioration of the water quality but do not cause any harm to other aquatic life, like fish .
D. Biomagnification refers to the decrease in concentration of the toxicant at successive trophic levels .

Answer

To solve the question, we need to analyze each statement provided and determine which one is correct.

### Step-by-Step Solution:

1. **Evaluate the First Statement**:
- The statement claims that 0.1% of impurities in sewage water consist of suspended solids like fecal matter, bacteria, and paper fibers.
- **Analysis**: While sewage water does contain impurities, the 0.1% impurities primarily consist of suspended solids like sand, silt, and clay. Fecal matter, bacteria, and paper fibers fall under colloidal materials and dissolved particles, not suspended solids.
- **Conclusion**: This statement is **incorrect**.

2. **Evaluate the Second Statement**:
- The statement mentions that mauve-colored flowers are a characteristic feature of the world's most problematic weed.
- **Analysis**: The world's most problematic weed is indeed the Water Hyacinth (Eichhornia crassipes), which is known for its mauve-colored flowers and rapid growth in aquatic environments.
- **Conclusion**: This statement is **correct**.

3. **Evaluate the Third Statement**:
- The statement claims that algal blooms cause deterioration of water quality but do not harm other aquatic life like fish.
- **Analysis**: Algal blooms can lead to decreased water quality and can be harmful to aquatic life, including fish, due to decreased oxygen levels and toxins produced by some algae.
- **Conclusion**: This statement is **incorrect**.

4. **Evaluate the Fourth Statement**:
- The statement refers to biomagnification as a decrease in concentration of the toxicant at successive trophic levels.
- **Analysis**: Biomagnification actually refers to the increase in concentration of toxic substances as they move up the food chain.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion:
The only correct statement is the **second statement** about mauve-colored flowers being a characteristic feature of the Water Hyacinth.