Which of the following statements about marginal tax rates is true?

a. A taxpayer's marginal rate can change with every transaction

b. As the marginal rate increases, the tax savings of an income-generating transaction decreases

c. As the marginal rate increases, the tax savings from a deduction increases

d. Both a taxpayer's marginal rate can change with every transaction and, as the marginal rate increases, the tax savings from a deduction increases