We're asked to figure out how Polanski has misunderstood Brewer. (What a rare question type!)
To paraphrase, Brewer says that all kids should be given the chance to play competitive sports because playing these sports is a chance to engage emotions and work towards being great at the sport.
Polanski replies that while sports will create some kids motivated to be great, not every kid wants to play competitive sports and forcing them to do so would turn them off of sports.
The issue, as (D) points out, is that Brewer never spoke about forcing kids to play. Brewer suggested all kids "be given the opportunity..."
(A) is out of scope. Neither discusses other aspects of life.
(B) is tempting, but neither party discusses winning. And, neither even says that playing sports is essential to anything.
(C) is incorrect because of degree. Neither discusses where relative amounts of effort should go.
(E) is similar to (B). While Brewer says that sports engages emotions and motivates kids, the link is not mentioned. More importantly, Polanski doesn't discuss the relationship between motivation and engagement.