Why Do Economists Study Sports Teams When Looking for Evidence

Why do economists study sports teams when looking for evidence of labor-market discrimination?

A) because the salaries paid to professional athletes exhibit the superstar phenomenon, which is highly correlated with discrimination
B) because all four United States professional sports leagues (football, basketball, hockey, and baseball) require discrimination studies every five years
C) because nonwhites comprise a majority of starters for many professional sports teams
D) because the wide availability of performance statistics allows economists to control for individual player productivity in ways that are difficult to do for other types of firms