of 5 - ZOOM + 1. Which of the following statements is true? a. Tax revenue from corporate income taxes is the largest source of tax revenue b. If a progressive tax rate system is used as a taxpayer's taxable income increases, a progressively lower tax rate is applied. C. Adam Smith established five criteria for a "good" tax structure in 1776: equity, certainty, convenience, economy and simplicity. d. The only objective of the federal income tax law is to raise revenues for government operations e. None of the answers provided is correct. A