After working for 25 years as personal fitness trainers while raising their kids, three sisters cashed in a total of $120 comma 000 in bonds and decided to open a small, neighborhood fitness center. they spent the $120 comma 000 on exercise equipment, advertising, computer equipment, and other furnishings for the business. for the next 3 years, they took in $145 comma 000 in revenue each year, paid themselves $33 comma 000 annually each, and rented a space in a strip mall for $22 comma 000 per year. before the investment, their $120 comma 000 in bonds were earning interest at a rate of 6 percent. are they now earning economic profits explain? your answer. a. they are earning profits of $115 comma 800, which takes into account the $7 comma 200 opportunity cost of their capital. b. they are earning profits of $16 comma 800, which takes into account the $7 comma 200 opportunity cost of their capital and the $99 comma 000 combined opportunity cost of their own labor. c. they are earning profits of $123 comma 000, which takes into account the opportunity cost of their capital. d. they are earning profits of $3 comma 000, which takes into account the $120 comma 000 opportunity cost of their capital.