Curd, milk, cheese and butter are produced with the help of:

Options

A. Yeast
B. Penicillium
C. Streptococcus
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which microorganism is involved in the production of curd, milk, cheese, and butter.

2. **Analyzing the Options**: The options provided are yeast, penicillium, streptococcus, or none of the above. We need to evaluate each option to determine which one is correct.

3. **Evaluating Yeast**: Yeast is primarily used in the fermentation process for baking products like bread. It is not involved in the production of curd, milk, cheese, or butter.

4. **Evaluating Penicillium**: Penicillium is a type of fungus known for producing the antibiotic penicillin. While it has various applications, it is not used in the production of curd, milk, cheese, or butter.

5. **Evaluating Streptococcus**: Certain species of the Streptococcus genus, such as Streptococcus lactis and Streptococcus thermophilus, are known to be involved in the fermentation process that leads to the production of curd, cheese, milk, and butter.

6. **Conclusion**: Based on the evaluations, the correct answer is **Streptococcus**.

**Final Answer**: C. Streptococcus

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