Which of the following is an example of a progressive tax?

Which of the following is an example of a progressive tax?
A . Personal income tax of 10% on earnings up to $10,000, then at 15% over $10,001
B . Corporate income tax of 20% on earnings up to $100,000, then at 10% over $100,000
C . Corporate income tax of 20% on all earnings
D . Personal income tax of 10% and corporate income tax of 20%

Answer: A