Answer:
From what I gathered from researching, I would say that Layer 2 is the correct answer to the question you asked.
Step-by-step explanation:
The reason I'd say it is Layer 2 is because the lower you look in a canyon, the farther back you look in time. Over that canyon's history, more layers are added on top of the rock and ground as erosion and weathering happen.
Layer 2 is the highest up, which means that it was added the most recent of the other layers. Although there are more things that could maybe be taken to account, the best answer I see from what information you were given in this question... Layer 2 is the correct answer.
Hope that helps!