16. which of the following is not an example of a deduction? a. interest on a mortgage b. taxable income c. state tax payments d. donation to charity

Taxable income is not deductible as that is the money that is what is being taxed. As a general rule, items that are deductible from your income are things that take away money from you taxable net or gross income, but generally are not normal expenditures like buying clothing or food. State tax payments, donations, and interest on a mortgage all take money away from you net and therefore are deductible.