Most people didn't get this one right, but I'll give you a break.  1952 was the last time the Democrats needed more than one ballot; Estes Kefauver was ahead on the first vote, but Adlai Stevenson won the nomination on the second. But the best answer is B - 1968.  That year, after LBJ dropped out of the race, and Robert F. Kennedy was assassinated, Eugene McCarthy had the most primary delegates.  But late entry Vice President Hubert Humphrey, without entering a single primary, rounded up enough support to win the nomination on the first ballot, though his nomination was not assured until he got to the Chicago convention, since he had won no primaries.