Which Statement Is True About the Lithosphere

Which statement is true about the lithosphere?

A) The lithosphere is thickest at the mid-ocean ridges because of the quantity of magma that flows up to the surface.
B) The lithosphere gets thicker as distance from the ridge increases, because it cools and the boundary between the lithosphere and asthenosphere occurs at greater depth.
C) The lithosphere maintains its thickness as distance from the ridge increases, because the boundary between the lithosphere and asthenosphere remains at a constant temperature and depth.
D) The lithosphere gets thinner as distance from the ridge increases, because decompression melting occurs with decreased pressure.