Which of the following is /are concerned with biotechnology?

Options

A. Biogas production
B. Sewage treatment
C. Biofertilizer
D. All of the above

Answer

To determine which of the options are concerned with biotechnology, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Biotechnology**:
- Biotechnology is a field that involves the use of living organisms or their products to develop or create different products and processes. It encompasses various applications including genetic engineering, bioprocessing, and bioremediation.

2. **Analyzing Option 1: Biogas Production**:
- Biogas production involves the anaerobic digestion of organic matter by microorganisms, particularly methanogens (methane-producing bacteria). This process is a classic example of biotechnology as it utilizes biological processes to produce energy (biogas).

3. **Analyzing Option 2: Sewage Treatment**:
- Sewage treatment involves the use of microorganisms to break down waste materials in sewage. Both aerobic and anaerobic bacteria are used in this process. This application also falls under biotechnology as it employs biological agents to treat wastewater.

4. **Analyzing Option 3: Bioreactor**:
- A bioreactor is a vessel or container in which biological reactions occur, often involving microorganisms or cells. Bioreactors are essential in biotechnology for processes like fermentation and bioproduction. Thus, this option is also related to biotechnology.

5. **Analyzing Option 4: All of These**:
- Since all the previous options (biogas production, sewage treatment, and bioreactor) are concerned with biotechnology, this option suggests that all of them are interconnected and relevant to the field.

6. **Conclusion**:
- Based on the analysis, all the options provided (biogas production, sewage treatment, and bioreactor) are concerned with biotechnology. Therefore, the correct answer is **Option 4: All of These**.