Answer: The fossils in Layer 2 are younger than those in Layer 1, and older than the fossils in layer 3. (assuming layer 1 is at the bottom, and layer 3 is at the top.)
Explanation: Think of how this stack of rocks formed. Layer 1 would have deposited first along with it's fossils, followed by 2, 3, etc. Layer 2's fossils would be younger than Layer 1, but older than Layer 3.