What is a "progressive tax" A "progressive tax" is

单项选择题

Taxes (税) are a big part in the United States. Most Americans pay city taxes, state taxes, social security (安全) taxes, sales taxes and the list seems endless.
The biggest tax for most Americans is that on the money they earn—the income tax. The personal income tax is called a "progressive tax" because it takes more from those who earn more. For example, a person who earns about 3,500 dollars a year will pay a tax of only about 3.5% of earning, but of the same person earned 85,000 dollars a year, he would pay an income tax of 35%.
Over the years the income tax has become more and more difficult for people to understand. Almost one half of all Americans now have to pay experts to prepare their tax reports. In fact, preparing taxes and giving tax advice have become a big industry in America.

What is a "progressive tax" A "progressive tax" is the tax ______.

A．collected for social progress
B．that increases with each passing year
C．that is collected from those who earn most
D．that varies (变化) according to how much money a person earns