Question

each layer of earth has different physical and chemical properties. this is because we classify the layers of earth based on what characteristic?
height of the layers
composition of the layers

Explanation:

The Earth's layers (like crust, mantle, core) are classified based on their composition (chemical and physical properties from what they're made of). Height of layers doesn't determine their properties; composition (materials, structure) does. So the correct option is about the composition of the layers.

Answer:

Composition of the layers