The taxpayers total marginal federal and state income tax rate is 30%. Which would the taxpayer prefer?

a. $1.00 taxable income rather than $.70 tax-exempt income.

b. $1.30 taxable income rather than $1.00 tax-exempt income.

c. $1.40 taxable income rather than $1.00 tax-exempt income.

d. $1.50 taxable income rather than $1.00 tax-exempt income.

e. Both (c) and (d) are correct.