In the given example, the story element that is most influenced over the others is C) setting.
The setting provides the context in which the characters interact and the plot unfolds. Mike Coward's situation of waiting under a tree for the rain to stop establishes not only the physical environment but also affects the characters' emotions and motivations, particularly his brother's impatience. The setting creates a backdrop that influences how the characters behave and how the plot develops, making it a critical element in this scenario.