The correct answer is: Only I and III are implicit.
The statement “Put a notice on the board that all the employees should come on time to office” implies that the officer believes that some employees are not coming on time. This is because the officer is asking his assistant to put up a notice reminding employees to come on time. However, the statement does not imply that all employees are coming late, or that employees will follow the instructions. It is possible that some employees are already coming on time, and that the officer is simply trying to remind everyone to be on time. It is also possible that some employees will not follow the instructions, even if they see the notice.
Therefore, only assumptions I and III are implicit in the statement. Assumption II is not implicit, because the statement does not say anything about whether or not employees read notices on the board.