Which of the Following Statements Is Correct

Which of the following statements is correct?

A) Vertical equity is the idea that taxpayers with similar abilities to pay taxes should pay the same amount.
B) Horizontal equity is the idea that taxes should be levied on a person according to how well that person can shoulder the burden.
C) A regressive tax would mean that high-income tax payers pay a larger fraction of their income in taxes than would low-income taxpayers.
D) A proportional tax would mean that high-income and low-income taxpayers pay the same fraction of income in taxes.