Total increase from Rs500 to Rs600 When output increases from 20 to 30 units Fixed costs are Rs200 Which of the following is true ?

A. Wine
B. Beer
C. Both wine and beer
D. Neither wine nor beer

A. Is the philosophy of free international trade?
B. Was a system of export promotion and barriers to imports practiced by governments?
C. Was praised by Adam Smith in the Wealth of Nations
D. Both (a) and (c)