Sam quit his job as an accountant with We Keep Books Accurately to open his own accounting firm. He earned $$40,000$ with the accounting firm We Keep Books Accurately. During the current year, Sam had revenues of $$150,000$ and total expenses of $$110,000.$ For Sam, the opportunity cost of going into business was$\_\_\_\_\_.$ Sam earned an $\_\_\_\_\_.$

a$.$

$0$; entrepreneurial loss of $$110,000.$

b$.$

$$110,000$; accounting loss of $$40,000$

c$.$

$$40,000$; accounting profit of $$40,000$

d$.$

$$150,000$; entrepreneurial profit of $$40,000.$