What prevents soil water from diffusing through endodermal cell walls?

A) the primary xylem bordering the endoderm
B) the pericycle that surrounds the vascular cylinder
C) transport proteins in endodermal cell walls
D) the Casparian strip between endodermal cells
E) a cuticle on the outside of the endoderm

The Casparian strip is a waxy barrier found in the cell walls of endodermal cells that surrounds the vascular cylinder in plants. This strip prevents water and solutes from passing through the cell walls and into the xylem via the apoplast pathway, forcing them to pass through the plasma membranes of endodermal cells and through transport proteins, allowing for selective absorption of necessary nutrients.