What is the main focus of the Sixteenth Amendment?

The main focus of the Sixteenth Amendment is the authority it grants Congress to levy income taxes without apportioning them among the states based on population. This amendment, ratified in 1913, effectively allowed the federal government to impose a direct tax on individual incomes, which was a significant shift in tax policy. Prior to this amendment, any direct tax had to be distributed across the states in a way that was proportional to their populations, which often made it difficult for the government to effectively raise funds.

Understanding the context of this amendment is crucial, as it arose from a historical period when the U.S. government sought more stable revenue sources to fund its obligations and programs. The income tax system established with the Sixteenth Amendment has evolved into a major source of federal revenue, impacting how the government operates and provides services today.

The other choices relate to significant historical issues but do not pertain to the focus of the Sixteenth Amendment, thus reinforcing that the correct answer relates specifically to Congress's power over income taxation.