Answer:
A) there a fixed number of stadium seats.
Explanation:
Price of tickets increases because the number of seats is fixed. Therefore, if the authority sells one ticket, one seat has been reduced. If there are 500 seats available and 200 tickets are sold, 300 seats are available. In that case, the supply remains the same. However, due to the increasing demand, the authority tries to increase the price. Therefore, option A is correct.