Why Do Plants Need an Endodermis in Their Roots

Why do plants need an endodermis in their roots?

A) to control the movement of dissolved ions into the xylem that would otherwise
B) concentrate in the shoot as a consequence of evaporation
C) to exclude mycorrhizal symbionts from access to the phloem
D) to keep air bubbles from entering the xylem
E) All of these choices are correct.