Which ones forms bloom in polluted water mostly-

Options

A. Cyanobacteria
B. Green algae
C. Red algae
D. Brown algae

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which organisms form blooms in polluted water. We need to identify the type of algae or bacteria that thrive in such conditions.

2. **Analyzing the Options**: We have four options to consider:
- A) Cyanobacteria
- B) Green Algae
- C) Red Algae
- D) Brown Algae

3. **Identifying Characteristics of Each Option**:
- **Cyanobacteria**: Also known as blue-green algae, these are capable of photosynthesis and can thrive in various water bodies. They are known for forming blooms, especially in nutrient-rich and polluted waters.
- **Green Algae**: While they can also grow in various conditions, they are not specifically known for forming blooms in polluted waters.
- **Red Algae**: Typically found in marine environments and not associated with blooms in polluted waters.
- **Brown Algae**: Mostly found in marine environments and not commonly associated with blooms in polluted waters.

4. **Conclusion**: Based on the characteristics and behaviors of the organisms listed, cyanobacteria (blue-green algae) are the ones that predominantly form blooms in polluted waters due to their ability to thrive in nutrient-rich environments.

5. **Final Answer**: The correct answer is **A) Cyanobacteria**.