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