Which amendment allowed for federal income taxes after being proposed by Congress?

The 16th Amendment is significant because it explicitly grants Congress the power to levy and collect income taxes without apportioning them among the states based on population. Ratified in 1913, this amendment transformed the federal government's ability to generate revenue, fundamentally changing the way in which government finances were structured. Prior to the 16th Amendment, income taxes were often deemed unconstitutional unless they were distributed based on states' populations, which made it difficult for the federal government to implement such taxes effectively.

In contrast, the other amendments listed do not relate to federal income tax. The 14th Amendment primarily addresses citizenship rights and equal protection under the law, while the 19th Amendment granted women the right to vote. The 10th Amendment focuses on the powers reserved to the states and the people, which does not involve federal taxation authority. Thus, the 16th Amendment is the correct answer as it directly pertains to the establishment and legal foundation for federal income taxes.