Final answer:
Thomas Jefferson and James Madison responded to the Alien and Sedition Acts through the Virginia and Kentucky Resolutions of 1798, arguing that the acts were unconstitutional and that states had the right to nullify them.
Step-by-step explanation:
The correct answer is Virginia & Kentucky Resolutions.
Thomas Jefferson and James Madison responded to the Alien and Sedition Acts by stating that the acts were unconstitutional and that states had the right to nullify them through the Virginia and Kentucky Resolutions of 1798. These resolutions argued that the acts were illegal and unconstitutional, and introduced the concept of nullification, which allowed states to reject federal laws they deemed unconstitutional.
Despite not gaining widespread support from other states, the Virginia and Kentucky Resolutions served as important political propaganda for the Republicans and contributed to the ongoing debate about states' rights and nullification.