Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Lithosphere and asthenosphere are layers based on physical properties. The outermost layer is the lithosphere . The lithosphere is the crust and the uppermost mantle. In terms of physical properties, this layer is rigid, solid, and brittle. It is easily cracked or broken. Answer: outermost layer
Output:
Which layer is the lithosphere located?