The correct reasons for why Congress decided the election of 1800 are:
- The popular vote was a tie.
- No candidate won the electoral vote.
In the election of 1800, Thomas Jefferson and Aaron Burr received an equal number of electoral votes, resulting in a tie. Since no candidate received a majority of electoral votes, the election was then decided by the House of Representatives, as mandated by the U.S. Constitution. The statement about not enough citizens voting does not apply to this situation.