An example of an amendment to the u. s. constitution that shows the principle of federalism is how the

26th amendment allows 18-year-old citizens to vote in state and national elections
10th amendment reserves rights to the states not assigned to the national government
16th amendment allows the federal government to collect income taxes from individuals
first amendment prevents states from taking away any of the people's rights to free speech

The correct answer is: 10th Amendment reserves rights to the states not assigned to the national government.

The key principle to Federalism is the fact that some powers are reserved to a centralized government, while others are distributed among states.

The 10th Amendment to the US Constitution brings this federalist principle and reservers some specific powers to the states.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )