What Best Describes the Shape of the Entire Vascular Cambium

Multiple Choice

What best describes the shape of the entire vascular cambium system in trees? Visualizing a pine tree helps with this question.

A) hollow cylinder with a smaller diameter at the base of the tree
B) hollow cylinder with a smaller diameter at the top of the tree
C) solid column of cells with a smaller diameter at the base of the tree
D) solid column of cells with a smaller diameter at the top of the tree