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.
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One of the most important was climate changes. As climate changed, nomads had to find new places to migrate to which led to people going to areas that were uninhabited before. Another was the development of agriculture which more or less ended the nomadic way of life when people started settling.
Requiring the vaccination of schoolchildren, even if their religion opposes it
