A tax of $20 on an income of $200,$40 on an income of $300,and $80 on an income of $400 is:

A) progressive.
B) proportional.
C) regressive.
D) constant-rate.

Constant-Rate

Pertaining to a process or quantity that changes over time at an unvarying speed or amount.

Progressive Tax

A tax system where the tax rate increases as the taxable amount increases, placing a heavier burden on wealthier taxpayers.