Answer:
C. Behind everything else
Step-by-step explanation:
In a game with three frames it is important to maintain balance and conformity, so that the three frames make sense together and establish a pleasant and aesthetically acceptable environment.
For the game to be harmonious it is important that the objects of Layer 1 appear behind everything else. However, this is not a rule that you have to follow to the letter, if your goal is not compliance and balance.