Answer:
O the levying of a federal income tax
Step-by-step explanation:
The Sixteenth Amendment passed in 1913 upheld the right of the United States government to charge a federal income tax. It was further supported by the Revenue Act of 1913. This aspect of the United States Constitution states;
"The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration."
This is today found in the Internal Revenue code and Title 26 of the United States Constitution. All citizens of the U.S are expected to pay the federal income tax.