What is the PGA of America known as?

The correct answer is that the PGA of America is known as the world's largest working sports organization. This designation emphasizes the active and professional nature of the members who are employed in the golf industry in various capacities, such as teaching professionals, club managers, and tournament organizers.

Being a "working" sports organization indicates that it focuses on the practical application of golf, including promoting the sport, training new professionals, and offering education and resources for those involved in golf as a profession. This distinguishes the PGA of America from other types of organizations that may have a broader or less employment-focused structure.

In this context, the other options do not capture the essence of what the PGA of America embodies. While it may have aspects of being a retail sports organization or a confederation, the emphasis on "working" highlights the ongoing, active participation of its members in the golf industry, which is the hallmark of the PGA of America.