It is an alphabet adapted from the Greeks that is used for Slavic languages.
When the framers designed the US Constitution they did not give the Federal government much power so power was balanced between States and Central Government. But the Federal government has gained more and more power over time. At the same time, the States were restricted over the years, when the Framers did not imagine doing so.
Both of these situations can be good or bad. For example, making the States respect the Bill of Rights was a good thing when individuals had their basic rights stripped on a State level. So making only the Federal government respect the Bill of Rights did not make much sense.
At the same time, the Federal Government has shown much power that was not designed and showed a few issues over the years, especially with the Executive Branch that had in a few opportunities overstepped its powers.
Answer: FEDERAL INCOME TAX
Explanation:
The most likely tax that follows the principle that states that people should pay based on their ability is the federal income tax. This tax is progressive as the high income earners pay a higher percentage as tax when compared to he low income earners.
The sales tax and doctors license fees aren't progressive, as the rich and the poor all pay same amount. This doesn't align with the principle.