The correct answer is Rocky Marciano.
Rocky Marciano was an American professional boxer who competed from 1947 to 1955. He is the only heavyweight champion to retire undefeated, with a record of 49 wins and 0 losses. Marciano was known for his powerful punches and his aggressive fighting style. He was inducted into the International Boxing Hall of Fame in 1959.
Lee Apperson was an American professional boxer who competed from 1913 to 1925. He had a record of 51 wins, 13 losses, and 1 draw. Apperson was known for his speed and his ability to take a punch. He was never a heavyweight champion, but he did challenge for the title on two occasions.
Larry Holmes was an American professional boxer who competed from 1973 to 2002. He is a former undisputed heavyweight champion of the world. Holmes had a record of 56 wins, 3 losses, and 2 draws. He is considered one of the greatest heavyweight boxers of all time.
Michael Spinks was an American professional boxer who competed from 1977 to 1995. He is a former undisputed light heavyweight champion of the world and the lineal heavyweight champion of the world. Spinks had a record of 31 wins, 1 loss, and 0 draws. He is the only boxer to have won the heavyweight championship of the world after previously winning the light heavyweight championship.
In conclusion, the correct answer is Rocky Marciano. He was the only heavyweight champion to retire undefeated, with a record of 49 wins and 0 losses.