Select the correct statement-

Options

A. Supply of `O_2` to the biogas plant will have negative effect
B. Starch in cereals as raw material is used in fermentation process of making beer
C. Distillation of wine is necessary as it prevents further fermentation and spoiling wine
D. All

Answer

To solve the question, we need to analyze the options provided regarding the effect of oxygen (O2) supply to a biogas plant.

### Step-by-Step Solution:

1. **Understanding Biogas Production**: Biogas is produced through anaerobic digestion, a process that occurs in the absence of oxygen. Microorganisms break down organic matter, producing methane and carbon dioxide.

2. **Analyzing the Options**:
- All options state that the supply of O2 to the biogas plant will have a negative effect. This suggests that introducing oxygen into the biogas production process is detrimental.

3. **Conclusion**: Since biogas production is an anaerobic process, the presence of oxygen would inhibit the activity of anaerobic bacteria, which are essential for the production of biogas. Therefore, all options correctly state that supplying O2 to the biogas plant will have a negative effect.

4. **Selecting the Correct Statement**: Since all options indicate the same negative effect of O2 supply, they are all correct. However, if the question requires selecting only one option, any of the options can be chosen as the correct statement.

### Final Answer:
All options (1, 2, 3, and 4) correctly state that the supply of O2 to the biogas plant will have a negative effect.

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