Which sentence best describes a regressive tax?

Which sentence best describes a regressive tax?

a. Regressive taxes place a higher burden on people who earn less compared to wealthier tax payers.

b. Regressive taxes place a higher burden on wealthy tax payers compared to people who earn less.

c. Regressive taxes result in poor tax payers paying no taxes.

d. Regressive taxes prevent tax rates from rising over time.