8. What is meant by a progressive tax? A regressive tax? A proportional tax? Comment on the progressivity or regressivity of each of the following taxes, indicating your assumption concerning tax incidence:

(a) the federal personal income tax,

(b) a 7 percent general sales tax,

(c) a federal excise tax on automobile tires,

(d) a municipal property tax on real estate,

(e) the federal corporate income tax.