Final answer:
Richard Nixon resigned the presidency due to his involvement in the Watergate scandal and the subsequent cover-up. This illegal activity led to his impeachment, and he chose to resign from office before he could be removed.
Step-by-step explanation:
Richard Nixon resigned the presidency due to his involvement in the Watergate scandal. The scandal began with a break-in at the Democratic National Committee's headquarters at the Watergate office complex, and as the investigation unfolded, it revealed that Nixon had conspired to use the CIA to cover up the break-in. This illegal activity led to Nixon's impeachment, and he chose to resign from office before he could be removed.