One Way to Kill a Tree Is to Girdle It

One way to kill a tree is to girdle it by cutting a groove a centimeter into the bark all around the trunk of the tree.The tree will typically survive that growing season,but will die over the winter.Which is the best explanation for this observation?

A) The phloem was cut, so water and nutrients cannot be taken up to the leaves.
B) The xylem was cut, so sugars cannot be transported to the roots.
C) The xylem was cut, so water and nutrients cannot be taken up to the leaves.
D) Cutting the bark allows access to pathogens that kill the tree.
E) The phloem was cut, so sugars cannot be transported to the roots.