Assertion: Only Lactobacillus lactis causes curdling of milk.
Reason: Only this bacteria can produce lactic acid.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
B. If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion.
C. If Assertion is true but the Reason is false.
D. If both Assertion and Reason are false.

Answer

To solve the question regarding the assertion and reason provided, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Only Lactobacillus lactis causes curdling of milk."
- We need to evaluate whether this statement is true or false.

2. **Evaluating the Assertion**:
- While Lactobacillus lactis is indeed a key bacterium involved in the curdling of milk, it is not the only bacterium that can cause this process. Other species of Lactobacillus, such as Lactobacillus bulgaricus, can also curdle milk.
- Therefore, the assertion is **false**.

3. **Understanding the Reason**:
- The reason states that "Only this bacteria can produce lactic acid."
- We need to evaluate whether this statement is true or false.

4. **Evaluating the Reason**:
- Lactic acid is produced by various bacteria, not just Lactobacillus lactis. Other bacteria, including different species of Lactobacillus and Streptococcus, can also produce lactic acid.
- Therefore, the reason is also **false**.

5. **Conclusion**:
- Since both the assertion and the reason are false, the correct answer is that both the assertion and reason are false.

### Final Answer:
Both the assertion and reason are false.

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