Based on the scientists' observations, Animal A and Animal C have very similar structures, and Animal A and Animal B have somewhat similar structures. Additionally, Animal B and Animal C have very similar structures. This suggests that Animal A is the most closely related to Animal C, indicating that they might share a more recent common ancestor.
Given that Animal A is more closely related to C, it makes sense for Animal A to appear earlier in the fossil record.
The most reasonable order based on this reasoning would be:
A, C, B
Therefore, the correct response is: A, C, B.