Final answer:
Scene 2, involving the protagonist finding a clue that leads them closer to solving the mystery, is most clearly the rising action as it builds up the tension and conflict leading to the climax.
Step-by-step explanation:
The rising action is a key component of the narrative structure in a story, which includes a series of events that build up to the climax. The question is about identifying which of the four scenes provided is most clearly depicting the rising action. Scene 2, where the protagonist discovers a clue leading them closer to the mystery, best fits the definition of rising action.
During rising action, characters encounter conflict, embark on journeys, and the tension in the story increases, which is exactly what happens when a protagonist finds a crucial clue.