The newspaper headline that BEST explains how the Sedition Act influenced partisan debate in the election of 1800 is:
D. “Criminalizing Slander Obstructs First Amendment Rights!”
This headline directly addresses the core issue of the Sedition Act, which was used by the Federalists to suppress opposition, especially from the Republicans. It highlights the conflict between government authority and the protection of free speech, a significant point of contention in the partisan debates of that era.