Monascus purpureus is a yeast used commercially :-

Options

A. citric acid
B. blood cholesterol lowering agent
C. ethanol
D. streptokinase

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: Monascus purpureus is a type of yeast that is commercially significant.

2. **Understand its Uses**: The primary commercial use of Monascus purpureus is as a cholesterol-lowering agent. This yeast produces substances known as monacolins, which can help reduce blood cholesterol levels.

3. **Evaluate the Options**: The question provides several options regarding the uses of Monascus purpureus. Among the options, we need to identify which one correctly describes its application.

4. **Eliminate Incorrect Options**:
- **Citric Acid**: This is produced by Aspergillus niger, not Monascus purpureus. Therefore, this option is incorrect.
- **Ethanol**: This is produced by Saccharomyces cerevisiae, another type of yeast. Hence, this option is also incorrect.
- **Blood Cholesterol Lowering Agent**: This option is correct as Monascus purpureus is known for its ability to lower cholesterol levels.

5. **Conclusion**: Based on the evaluation of the options, the correct answer is that Monascus purpureus is used as a blood cholesterol-lowering agent.

**Final Answer**: Monascus purpureus is used commercially as a blood cholesterol-lowering agent.

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