Casien present in milk, which is -

Options

A. Bacterium
B. sugar
C. protein
D. fat

Answer

**Step-by-Step Solution:**

1. **Understanding Casein**: The question asks about casein, which is a component found in milk. We need to identify what casein is.

2. **Identifying the Type of Substance**: Casein is classified as a phosphoprotein. This means it is a type of protein that contains phosphate groups.

3. **Occurrence in Milk**: Casein is predominantly found in mammalian milk. For example, in cow's milk, it constitutes about 80% of the total protein content. In human milk, it accounts for around 20-45% of the protein.

4. **Evaluating the Options**: The question provides four options: bacteria, sugar, protein, and fat. We need to evaluate each option:
- **Bacteria**: This is incorrect as casein is not a bacteria.
- **Sugar**: This is also incorrect as casein is not a sugar.
- **Protein**: This option is correct since casein is indeed a protein.
- **Fat**: This is incorrect as casein is not a fat.

5. **Conclusion**: Based on the evaluation, the correct answer is that casein present in milk is a protein.

**Final Answer**: Casein present in milk is a protein.

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