Why do authors introduce subplots?

Authors introduce subplots primarily to **d. to create mystery, tension, or surprise**. Subplots can add depth to the main narrative, enrich character development, and enhance the overall storytelling experience by weaving in additional conflicts or themes that complement or contrast with the main plot. While subplots can also support a certain tone or mood (a), appeal to different reader interests (b), or extend the story (c), their primary function often revolves around building complexity and engaging the reader through various narrative twists.