The detailed description of the game's complex story and its impact on gameplay should be included in the "project highlights" section of the game design document. Hence, option D is correct.
The detailed description of the complex story and its significance to gameplay in an action-adventure game should be included in the "project highlights" section of the game design document (option d). This section typically focuses on the unique selling points, key features, and distinguishing aspects of the game that set it apart from others in the same genre.
In the context of an action-adventure game, the narrative is a critical component that enhances player engagement and immersion. By elaborating on the intricacies of the story, the game design document communicates how the narrative elements contribute to the overall gaming experience. This information helps stakeholders, including developers and investors, understand the creative and innovative aspects of the game.