Short-run costs — practice question

The table presents the marginal tax rates paid by a country’s taxpayers at various income levels. Which description correctly applies to this tax?

• AIt is regressive over the entire range of income.
• BIt is proportional over the income range $4001 - $20 000.
• CIt is proportional over the range of income above $20 000.
• DIt is progressive over the range of income above $4000.