Which event marked the beginning of segregation in professional baseball in the late 1800s?

The correct answer is D) baseball owners reached an agreement on segregation.

The event that marked the beginning of segregation in professional baseball in the late 1800s was that baseball owners reached an agreement on segregation.

In 1867, Base Ball saw the beginning of segregation in this sport. During the convention in Harrisburg, Pennsylvania, the owners did not allow a black team to be part of the league. From then on, Major League Baseball white players did not want to play with black players in their teams or against other teams that had black players. It was until Jakie Robinson success as a player, that things began to change.

The other options of the question were, a) Congress passed a law segregating all sports, b) Branch Ricky fought for segregation before the Supreme Court, and c) an executive order requiring segregation was issued.  

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