Select the statement that indicates protectionism

Can someone me write a paragraph on this topic i feel confused

Why was the sixteenth amendment important to woodrow wilson’s efforts to regulate the economy? a) the sixteenth amendment lowered interest rates charged by banks. b) the sixteenth amendment allowed congress to levy an income tax c) the sixteenth amendment lowered tariffs on imported goods d) the sixteenth amendment allowed congress to break up monopolies

Indicate the point where a monopoly will set its price