Final answer:
Mark McCormack's sports marketing agency, IMG, began through a relationship with players of the sport golf.
Step-by-step explanation:
The sport that Mark McCormack's sports marketing agency, IMG, began through a relationship with players is golf.
In the 1920s, famous athletes in various sports gained significant popularity. Jack Dempsey was a well-known boxer, Red Grange's college football career fascinated many, and tennis greats Bill Tilden and Helen Wills, as well as golfing great Bobby Jones, became household names.
Figure 5.1.10 mentions that Babe Ruth was the first global icon of team sports, which further emphasizes the prominence of baseball during that time.