Answer: Nixon was the first president to resign from office.
Details/context:
John F. Kennedy had defeated Richard Nixon in the presidential election of 1960 -- so disregard answer choice #3. Richard Nixon won the presidential election of 1968 and was re-elected to the office in 1972.
Ultimately, Richard Nixon resigned the presidency to avoid impeachment for his role in covering up the Watergate break-ins. (So you can disregard answer choice #2, because he resigned before impeachment could happen.)
Nixon's role in Watergate was especially in his efforts and those of members of his staff to cover up what had happened. Ultimately, the Watergate affair brought down the Nixon presidency. He was the first--and is the only--US president ever to resign from the office.
