Step 1: Understanding the question.
Monascus purpureus, a type of yeast, is used commercially for the production of citric acid. It is widely used in food and pharmaceutical industries.
Step 2: Commercial uses of Monascus purpureus.
Monascus purpureus is primarily known for its ability to produce citric acid, which is used in various food processing applications and in medicines.
Step 3: Analysis of the options.
- (A) Ethanol: Incorrect. Monascus purpureus is not used in ethanol production.
- (B) Streptokinase: Incorrect. Streptokinase is produced by bacteria, not Monascus purpureus.
- (C) Citric acid: Correct. Monascus purpureus is commercially used for the production of citric acid.
- (D) Statins: Incorrect. Statins are not produced by Monascus purpureus.
Step 4: Conclusion.
The correct answer is (C) Citric acid, as Monascus purpureus is commercially used in its production.
Final Answer: Citric acid.