Suppose your friend bas invited you for lunch and offers to pay for it and any transportation costs you may incur to travel to the restaurant. Which of the following represents an opportunity cost to you of accepting this "free" lunch?

a$.$ Only what coudd be bought with the marey your fnend spent on the lunch and transponation.

b$.$ There is no cpporturity cost to you.

c$.$ Wharever dis you could have done duting the time spenchaving lunch weth your friend.

d$.$ The stitematove ures of the rewources used to make the lunch.