Atax that imposes a higher percentage rate of taxation on low incomes rather than high incomes is known as
a. a. proportional tax
c. excise tax
b. progressive tax
d. regressive tax

D. it's a regressive tax

To help you understand. Let's say that the tax is 20% for an income below 3000$ and 10% for the part of the income above 3000$. This is a regressive tax. 

The opposite of this is the progressive tax. Proportional tax have a flat rate and excise tax is something entirely different.