Final answer:
The Legislative branch has changed the most since the Founding, with examples including the expansion of voting rights and the evolution of Congress's powers.
Step-by-step explanation:
The branch of federal government that has changed the most since the Founding is the Legislative branch. This branch, which is responsible for making laws, has undergone significant changes over time. One example is the expansion of voting rights, with the 15th, 19th, 24th, and 26th Amendments granting suffrage to different groups of citizens. Additionally, the powers and responsibilities of Congress have evolved and been shaped through court decisions and legal interpretations.
Learn more about change in the Legislative branch since the Founding