Which term describes a character's underlying reasons for their actions?

The term that describes a character's underlying reasons for their actions is "motive." A character's motive refers to the motivations that drive them to behave in certain ways, shaped by their desires, fears, values, and experiences. Understanding a character's motive provides insight into their actions and decisions, allowing readers to empathize with or analyze the character more deeply.

In contrast, conflict refers to the struggle between opposing forces within a story, which can involve characters, societal norms, or even internal dilemmas. Theme encompasses the central ideas or messages conveyed by a work of literature, revealing deeper meanings but not specifically focused on individual characters. Symbolism involves the use of symbols to represent ideas or concepts, which adds layers of meaning but does not directly address the reasons behind a character's behavior. Therefore, "motive" is the most accurate term for understanding why a character acts as they do.