The food can be kept in the fridge for longer duration because

Options

A. bacteria are not able to infect
B. bacterial multiplication is reduced
C. low temperature causes death of bacteria
D. growth of useful bacteria reduces the harmful bacteria

Answer

To answer the question, "The food can be kept in the fridge for longer duration because," we need to analyze the options provided and understand the role of temperature in bacterial growth.

### Step-by-Step Solution:

1. **Understanding Bacterial Growth**: Bacteria thrive and multiply rapidly at room temperature. They require certain conditions, such as warmth and moisture, to grow effectively.

2. **Effect of Low Temperature**: When food is stored in the fridge, the temperature is significantly lowered. This cold environment slows down the metabolic processes of bacteria.

3. **Bacterial Multiplication**: At lower temperatures, the rate of bacterial multiplication is reduced. Bacteria may enter a dormant state where they are not actively reproducing, which helps in preserving the food.

4. **Evaluating the Options**:
- **Option A**: "Bacteria are not able to infect" - This is not entirely accurate as some bacteria can still survive, but their multiplication is what is primarily affected.
- **Option B**: "Bacterial multiplication is reduced" - This is correct because the cold temperature slows down their growth.
- **Option C**: "Low temperature causes death of bacteria" - While some bacteria may die, many can survive at low temperatures; hence this option is misleading.
- **Option D**: "Growth of useful bacteria reduces the harmful bacteria" - This is not relevant to the preservation of food in the fridge.

5. **Conclusion**: The best answer is **Option B**, which states that "Bacterial multiplication is reduced." This is the reason why food can be kept in the fridge for a longer duration.

### Final Answer:
**B. Bacterial multiplication is reduced.**