The correct answer is: Only II is implicit.
The statement says that the circus authorities decided to continue the show for another fortnight which includes two weekends. This means that the authorities are confident that they will be able to attract a good number of people to the show during the next fortnight. This confidence is based on the fact that the tickets sold during the last seven days were good.
Assumption I: People may not turn up on weekdays.
This assumption is not implicit in the statement. The statement does not say anything about whether people will turn up on weekdays or not. It is possible that people will turn up on weekdays as well.
Assumption II: The average number of people who will be visiting circus will be more or less same as that of the last seven days.
This assumption is implicit in the statement. The statement says that the circus authorities decided to continue the show for another fortnight which includes two weekends. This means that the authorities are confident that they will be able to attract a good number of people to the show during the next fortnight. This confidence is based on the fact that the tickets sold during the last seven days were good.
Assumption III: There may not be enough response at other places.
This assumption is not implicit in the statement. The statement does not say anything about whether there will be enough response at other places or not. It is possible that there will be enough response at other places as well.
Therefore, the only implicit assumption is II.