Final answer:
President Richard Nixon resigned under threat of impeachment due to the Watergate scandal and a cover-up of the break-in at the DNC's headquarters.
Step-by-step explanation:
President Richard Nixon resigned under threat of impeachment due to a scandal involving stolen information. The scandal, known as the Watergate scandal, revolved around the break-in at the DNC's headquarters at the Watergate office complex. As the investigation unfolded, evidence revealed that Nixon and his advisors were involved in the cover-up of the break-in. Facing impeachment, Nixon chose to resign from office on August 8, 1974, becoming the first president to do so.