State: Two usefulness of Lactic acid bacteria. (LAB).

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion .
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution

1. **Identify Lactic Acid Bacteria (LAB)**: Lactic acid bacteria are a group of beneficial bacteria that play a crucial role in food fermentation and gut health.

2. **Common Food Sources**: LAB are commonly found in fermented foods such as curd (yogurt) and yogurt itself. These foods are rich in LAB due to the fermentation process.

3. **First Usefulness - Nutritional Quality**: One of the main usefulness of LAB is that they improve the nutritional quality of food. Specifically, they enhance the levels of vitamin B12 in dairy products like curd and yogurt. This is important for maintaining good health, as vitamin B12 is essential for nerve function and the production of DNA and red blood cells.

4. **Second Usefulness - Gut Health**: The second usefulness of LAB is their positive impact on gut health. They help in maintaining a healthy balance of gut microbiota by inhibiting the growth of disease-causing microbes. This can lead to improved digestion and overall gut health.

### Summary of Usefulness
- **Improves Nutritional Quality**: Increases vitamin B12 content in foods like curd and yogurt.
- **Promotes Gut Health**: Helps in controlling harmful microbes in the digestive system.

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