Read the following passage and mark the letter A, B, C, or on your answer sheet to indicate the correct answer to each of the questions from 18 to 22.

 Edward Patrick Eagan was born on April 26th 1897 in Denver, Colorado, and his father died in a railroad accident when Eagan was only one year old. He and his four brothers were raised by his mother, who earned a small income from teaching foreign languages.

 Inspired by Frank Marriwell, the hero of a series of popular novels for boys, Eagan pursued an education for himself and an interest in boxing. He attended the University of Denver for a year before serving in the U.S. army as an artillery lieutenant during World War I. After the war, he entered Yale University and while studying there, won the US national amateur heavyweight boxing title. He graduated from Yale in 1921, attended Harvard Law School, and received a Rhodes scholarship to the University of Oxford where he received his A.M. in 1928.

 While studying at Oxford, Eagan became the first American to win the British amateur boxing championship. Eagan won his first gold medal as a light heavyweight boxer at the 1920 Olympic Games in Antwerp, Belgium. Eagan also fought at the 1924 Olympics in Paris as a heavyweight but failed to get a medal. Though he had taken up the sport just three weeks before the competition, he managed to win a second gold medal as a member of four-man bobsled team at the 1932 Olympics in Lake Placid, New York. Thus, he became the only athlete to win gold medals at both the Summer and Winter Olympics.

(Adapted from "Peteson's Master TOEFL Reading Skills)

What is the main idea of the passage?