Select the correct statement

Options

A. Acetobacter aceti produces citric acid
B. Saccharomyces cerevisiae is used as clot buster
C. Penicillium notatum restrict the growth of Staphylococci
D. methanogens are found in aerobic conditions

Explanation

To solve the question "Select the correct statement," we will evaluate each of the provided statements one by one.

### Step 1: Evaluate the first statement
**Statement:** Acetobacter aceti produces citric acid.
**Analysis:** This statement is incorrect. Acetobacter aceti is known for producing acetic acid (CH3COOH), not citric acid. Citric acid is produced by the fungus Aspergillus niger.
**Conclusion:** Incorrect.

### Step 2: Evaluate the second statement
**Statement:** Saccharomyces cerevisiae is used as a clot buster.
**Analysis:** This statement is also incorrect. Saccharomyces cerevisiae is a type of yeast commonly known as brewer's yeast. It is primarily used in the production of alcoholic beverages and in baking, not as a clot buster.
**Conclusion:** Incorrect.

### Step 3: Evaluate the third statement
**Statement:** Penicillium nautitum restricts the growth of staphylococci.
**Analysis:** This statement is correct. Penicillium nautitum is a fungus that produces penicillin, which is an antibiotic effective against certain bacteria, including staphylococci. Thus, it does restrict the growth of these bacteria.
**Conclusion:** Correct.

### Step 4: Evaluate the fourth statement
**Statement:** Methanogens are found in aerobic conditions.
**Analysis:** This statement is incorrect. Methanogens are a group of archaea that produce methane and thrive in anaerobic conditions, meaning they do not require oxygen to survive.
**Conclusion:** Incorrect.

### Final Conclusion
After evaluating all statements, the only correct statement is the third one: "Penicillium nautitum restricts the growth of staphylococci."