If a Beaver Eats the Bark All the Way Around

If a beaver eats the bark all the way around a tree trunk (a process called "girdling") , why does the tree die?

A) The tree is susceptible to insect and fungal diseases.
B) The phloem is damaged, and the transport of sugars ceases.
C) Cells of the lateral meristem can no longer continue to divide.
D) Water and minerals are no longer supplied to the leaves.
E) The tree cannot continue to photosynthesize.