Which of the following can be used as bacteriological filter

Options

A. Gelidium
B. Batrachospermum
C. Oscillatoria
D. Cymbella.

Explanation

To determine which of the given options can be used as a bacteriological filter, we need to analyze each option based on their characteristics and functions.

### Step-by-Step Solution:

1. **Understanding Bacteriological Filters**:
- A bacteriological filter is a fine filter designed to prevent the passage of bacteria.
- It has pores that are typically between 0.5 to 5 microns in diameter, allowing it to remove bacteria from solutions while letting smaller entities, like viruses, pass through.

2. **Analyzing the Options**:
- **Option 1: Gelidium**
- Gelidium is a type of red algae and does not have the structure necessary to function as a bacteriological filter.
- **Conclusion**: Not suitable.

- **Option 2: Bactericospermum**
- Bactericospermum is also not recognized for its use as a bacteriological filter.
- **Conclusion**: Not suitable.

- **Option 3: Oscillatoria**
- Oscillatoria is a genus of cyanobacteria (blue-green algae) and does not serve as a bacteriological filter.
- **Conclusion**: Not suitable.

- **Option 4: Cymbella**
- Cymbella is a genus of diatoms, which are known to have specialized structures called apical pore fields.
- These pores can effectively filter out bacteria due to their size and arrangement.
- **Conclusion**: Suitable as a bacteriological filter.

3. **Final Answer**:
- Based on the analysis, the correct answer is **Option 4: Cymbella**. It is the only option that can be used as a bacteriological filter due to its specialized pore structures.