The statement that best explains the author's choice to include both a lavish château and a jungle as the setting for "The Most Dangerous Game" is:
It heightens the contrast between civilized and uncivilized worlds.
This contrast is central to the story, emphasizing the themes of civilization versus savagery and the moral implications of hunting and survival. The château represents civilization and luxury, while the jungle symbolizes the primal instincts and the struggle for survival.