Answer: b. rewards that are intrinsic and dynamics that are free-flowing.
Sport is a form of competitive activity, either in the form of a game or a physical challenge. It is meant to maintain or improve a particular set of skills, and in some cases, provide entertainment.
While the concept is similar to play, playing offers intrinsic rewards (it is not done for the purpose of winning or losing, but for its own sake). Also, playing involves free-flowing dynamics, which means there is no strongly dictated rules and no penalties for breaking them. Even normal rules of society can be broken (like pretending an alternate universe). On the other hand, sports tend to have codified rules that are essential to the practice.