Which of the following is an example of a permanent difference between pretax GAAP accounting income and taxable income?
a. Straight-line depreciation is used for book purposes, but accelerated depreciation is used for tax purposes
b. Warranty expense is recognized in the year of sale for book purposes, but for tax purposes are deductible only when warranty expenditures are made.
c. Bad debt expense is estimated using an allowance method for book purposes, but the direct write-off method is used for tax purposes.
d. Interest earned on municipal bonds is tax exempt for federal income tax