Citric acid is obtained from:

Options

A. Aspergillus niger
B. Streptococci
C. Penicillium notatum
D. Saccharomyces cerevisiae

Explanation

**Step-by-Step Solution:**

1. **Understanding Citric Acid**: Begin by recognizing that citric acid is a weak organic acid commonly used in food and beverages for flavoring and preservation.

2. **Identifying the Source**: Citric acid is primarily obtained from the fungus known as **Aspergillus niger**. This organism is capable of fermenting sugars to produce citric acid.

3. **Exploring Other Options**:
- **Streptococci**: This is a genus of bacteria from which we obtain **streptokinase**, an enzyme used to dissolve blood clots.
- **Penicillium notatum**: This mold is known for producing **penicillin**, a widely used antibiotic.
- **Saccharomyces cerevisiae**: Commonly known as baker's or brewer's yeast, it is primarily used in the production of bread and alcohol, not citric acid.

4. **Conclusion**: After evaluating the options, it is clear that citric acid is specifically obtained from **Aspergillus niger**.

**Final Answer**: Citric acid is obtained from **Aspergillus niger**.

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