Read the passage.

(1) Many American men were drafted during World War II. (2) Many other men volunteered to serve. (3) In fact, so many men entered the armed services that professional baseball experienced a shortage of good players. (4) Philip K. Wrigley had an interesting solution to the problem. (5) He started a new league. (6) It was called the All-American Girls Professional Baseball League (AAGPBL). (7) To find good players, he scouted women’s softball clubs. (8) They were very popular at that time. (9) The AAGPBL was a hit. (10) In 1948, the year in which the league reached its high point of popularity, more than a million fans came to watch AAGPBL games. (11) The league produced many fine players, including Mary “Bonnie” Baker. (12) Dorothy Kamenshek was also a fine player. (13) After World War II ended, the AAGPBL declined in popularity. (14) In 1954, the league was disbanded.
Which is the most effective way to combine sentences (5) and (6)?

a-The All-American Girls Professional Baseball League (AAGPBL), a new league, started by him.
b-The All-American Girls Professional Baseball League (AAGPBL) was the new league he started.
c-He started a new league, and it was the All-American Girls Professional Baseball League (AAGPBL).
d-He started a new league called the All-American Girls Professional Baseball League (AAGPBL).

Explanation: In the given excerpt we can see the description of how the professional baseball experienced a shortage of good players because many of them volunteered to serve in the World War II, and how this caused the foundation of the All-American Girls Professional Baseball League. The most effective way to combine sentence 5 and 6 in order to avoid repetition is "He started a new league called the All-American Girls Professional Baseball League (AAGPBL)."