Indicate whether the following book-tax differences produce deferred tax assets, deferred tax liabilities, or neither. Consider each

Question:

Indicate whether the following book-tax differences produce deferred tax assets, deferred tax liabilities, or neither. Consider each item independently.
a. Book depreciation in excess of tax depreciation.
b. Tax depreciation in excess of book depreciation.
c. Increase in the allowance for doubtful accounts.
d. Increase in the reserve for warranty settlements.
e. Energy tax credits.
f. A current-year NOL.