Explanation:

To determine the ratio of time taken by the man walking from point A to B and back from B to A, consider the following:

- Time Calculation:

- Time taken from A to B = Distance / Speed = D / 6 hours

- Time taken from B to A = Distance / Speed = D / 10 hours

- Ratio of Times:

- The ratio of time taken from A to B to B to A is (D / 6) : (D / 10)

- Simplifying, this becomes 10 : 6

- Further simplification leads to 5:3

- Given Options:

- Option 1: 4 : 3

- Option 2: 5 : 4

- Option 3: 5 : 3

- Option 4: 5 : 2

- Conclusion:

- The correct ratio of times is 5 : 3.