Suppose the city of Edmonton wants to set the price of admission to the ice castle so that everyone can afford to see the attraction. They set the price of admission at $10 but people can sell the same tickets for $35 or more on the black market. The true cost (i.e., opportunity cost) in dollars to someone going to the ice castles is at least:

a) 25$

b) 35$

c) 10$

d) 45$