The progressive income tax was made possible by which amendment?

The progressive income tax was made possible by the 16th Amendment to the United States Constitution, ratified in 1913. This amendment granted the federal government the authority to levy an income tax without apportioning it among the states based on population. Prior to the 16th Amendment, the federal government relied more on tariffs and excise taxes for revenue, which often placed a heavier burden on lower-income individuals and families.

The implementation of the progressive income tax was a significant advancement in taxation, as it allowed for tax rates to increase with the taxpayer's ability to pay, thereby creating a more equitable financial system. This system reflects the principle that those who earn more should contribute a larger percentage of their income to support governmental functions and services.

The other amendments listed do not pertain to taxation. The 17th Amendment deals with the direct election of senators, the 18th Amendment established Prohibition, and the 19th Amendment granted women the right to vote. Therefore, the 16th Amendment is the correct answer regarding the foundation of the progressive income tax.