Dudheri Lal has two jars. Jar A is completely, filled with milk and another jar B is totally empty. Before setting the milk in a town he transferred some milk in to the empty jar B then he fill the jar A with water. Once again, he transferred the mixture of milk from A to B so that B is completely filled. Which one of the following is correct?

Options

A. Concentration of milk in B cannot be less than `75%`
B. Concentration of milk in B cannot be greater than `75%`
C. Concentration of milk is always `75%`
D. none of these

Answer

To solve the problem, we will analyze the steps Dudheri Lal took while transferring milk and water between the two jars.

### Step-by-Step Solution:

1. **Initial Setup**:
- Jar A is filled with 100 liters of milk.
- Jar B is empty (0 liters).

2. **First Transfer**:
- Dudheri Lal transfers some milk from Jar A to Jar B. Let's assume he transfers 50 liters of milk.
- Now, Jar A has 50 liters of milk left, and Jar B has 50 liters of milk.

3. **Filling Jar A with Water**:
- Dudheri Lal fills Jar A with water to make it full again. Since Jar A originally had 100 liters and now has 50 liters of milk, he adds 50 liters of water.
- Now, Jar A contains 50 liters of milk and 50 liters of water.

4. **Second Transfer**:
- Dudheri Lal transfers the mixture from Jar A to Jar B until Jar B is completely filled. Since Jar B already has 50 liters of milk, it can take another 50 liters.
- The mixture in Jar A is now 50% milk and 50% water (50 liters of each).

5. **Calculating the Transfer**:
- When Dudheri Lal transfers 50 liters from Jar A to Jar B, he is transferring a mixture that consists of 50% milk and 50% water.
- Therefore, in the 50 liters transferred, there will be:
- 25 liters of milk (50% of 50 liters)
- 25 liters of water (50% of 50 liters)
- After this transfer, Jar B will now contain:
- 50 liters (initial milk) + 25 liters (transferred milk) = 75 liters of milk
- 25 liters (transferred water)

6. **Final Composition in Jar B**:
- Jar B now has a total of 100 liters of liquid, which consists of:
- 75 liters of milk
- 25 liters of water
- Therefore, the concentration of milk in Jar B is 75%.

### Conclusion:
After the two transfers, Jar B contains 75% milk and 25% water.