Explanation:

Let’s break down the problem:

- Total road to construct: 6 km in 200 days.

- Total people initially: 140.

- Work done in 60 days: 1.5 km.

- Remaining road: 6 - 1.5 = 4.5 km.

- Remaining days: 200 - 60 = 140 days.

- In 60 days, 1.5 km by 140 people, so 1 km by 140 × 60 / 1.5 = 5600 man-days/km.

- So, 4.5 km needs 4.5 × 5600 = 25,200 man-days.

- People required to complete in 140 days: 25,200 / 140 = 180.

- Additional people needed: 180 - 140 = 40.

Explanation of options:

- Option 1: 40 – This is the correct answer.

- Option 2: 43 – Too high, calculation mismatch.

- Option 3: 45 – Slightly higher, again not matching calculated requirement.

- Option 4: 67 – Much too high, not supported by calculations.

Correct Answer: Option 1 (40).