Explanation:

- Let's solve the problem step-by-step:

- Initial Scenario: 36 persons x 8 hours/day x 12 days = Total hours required for 3 units of work.

- Calculate total hours: 36 x 8 x 12 = 3456 hours for 3 units.

- Therefore, 1 unit = 3456 / 3 = 1152 hours.

- New Scenario:

- Needed for 5 units: 1152 x 5 = 5760 total hours.

- Task is to find the number of persons required for 5760 hours, in 16 days, working 6 hours a day.

- Calculate required persons x 6 x 16 = 5760 hours.

- Solve for persons: Persons = 5760 / (16 x 6) = 60 persons.

- Conclusion:

- 60 persons are required.

- Therefore, the correct option is Option:1.

- Option 1: 60