All the options you provided can represent different ways in which a theme can be presented in a story. However, if you are looking for the one that best describes how a theme typically emerges, the most fitting choice would be:
C: it is introduced early and develops over the course of the story.
This option reflects how themes are often established through various elements like character development, plot progression, and recurring motifs, becoming clearer as the narrative unfolds.
Option D also holds some truth, as themes can often be inferred rather than stated directly. However, C emphasizes the development aspect, which is crucial to how themes are experienced in storytelling.