Question

a person’s tax obligation divided by his income is called his
marginal social tax rate
marginal private tax rate
margin tax rate
average tax rate

Explanation:

To determine the correct term, we analyze each option:

• "Marginal social tax rate" and "marginal private tax rate" relate to social/private aspects of marginal tax, not the ratio of total tax to income.
• "Margin tax rate" is an incorrect term (correct is "marginal tax rate", which is the tax rate on an additional dollar of income).
• "Average tax rate" is defined as total tax obligation (tax paid) divided by total income, which matches the description.

Answer:

D. average tax rate