You own a building that has four possible uses: a cafe, a craft store, a hardware store, and a bookstore. The value of the building in each use is $$2,000$;$$3,000$;$$4,000$; and $$5,000,$ respectively. You decide to open a hardware store. The opportunity cost of using this building for a hardware store is

a$)$ $$2,000,$ the value if the building is used as a cafe.

b$)$ $$3,000,$ the value if the building is used as a craft store.

c$)$ $$10,000,$ the sum of the values if the building is used for a cafe, a craft store, or a bookstore.

d$)$ $$5,000,$ the value if you rented the building to someone else to use as a bookstore