The Ability-To-Pay Principle of Tax Fairness Is Equivalent to Which

The ability-to-pay principle of tax fairness is equivalent to which of the following?

A) A proportional income tax structure.
B) A regressive income tax structure.
C) Collecting more taxes from people who can more easily bear the burden.
D) Collecting taxes from those who benefit the most from the provision of public services.
E) Concern about only horizontal equity and no concern about vertical equity.