Assertion (A) : The imposition of a per unit tax causes the monopolist's average cost and marginal cost curves to shift up.Reason (R) : The per unit tax is like a variable cost.

Public finance is the study of the role of the government in the economy. It is the branch of economics that assesses the government revenue and government expenditure of the public authorities and the adjustment of one or the other to achieve desirable effects and avoid undesirable ones.