Jack lived in a block with two-family homes. He finished his third floor for his family and when his children left home, he wanted to rent the floor as an apartment. The town enacted a zoning ordinance restricting occupancy of the building to a maximum of two unrelated families. Jack's best argument for waiving the ordinance is:

a. he can make more money renting two floors.
b. he cannot meet the costs of maintaining the building unless he rents both floors.
c. he is not going to add any more occupants to the building.
d. he was using the third floor as an apartment for rent before the zoning ordinance was enacted.

d