Which of the Following Reasons Might Explain, at Least in Part

Which of the following reasons might explain, at least in part, why changes in federal tax revenues tend to mitigate changes in aggregate demand?

A) The federal income tax rate is computed as a proportion of disposable income.
B) Federal income tax rates are progressive and thus increase with disposable income.
C) All kinds of taxes discourage work and thus reduce GDP, but the income tax creates the smallest of these work disincentives.
D) The federal income tax is constructed so that the middle-class taxpayer pays the largest share.
E) None of the above.