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 ʺgirdlingʺ) , why does the tree die?

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