A Higher Marginal Income Tax Rate Reduces Incentives to Work

A higher marginal income tax rate reduces incentives to work because:

A) leisure and other non-market activities aren't taxed, and so their relative price goes down.
B) leisure and other non-market activities aren't taxed, and so their relative price goes up.
C) the opportunity cost of leisure remains constant while after-tax wages fall.
D) the opportunity cost of leisure increases with the marginal income tax rate.