Which of the Following Best Matches the Description

Which of the following best matches the description?
-A thin flowing layer of the earth just below the outer mantle.

A) weathering
B) parent material
C) friable
D) soil profile
E) humus
F) chemical weathering
G) terrace
H) soil structure
I) terrace.
J) mechanical weathering
K) leaching
L) contour farming
M) loam
N) horizon
O) windbreak
P) soil texture
Q) lithosphere
R) asthenosphere