Suppose the tax rate structure is such that a household with an annual taxable income of less than $15,000 pays 60% in taxes; a household with annual taxable income of $15,000 to $30,000 pays 30%; and a household with annual taxable income of $30,000 to $60,000 pays 15% in taxes. What type of tax does this system exemplify? Multiple choice question. a proportional tax a progressive tax a regressive tax a flat tax a marginal tax