Which of the Following Is a Primary Difference Between Ectomycorrhizae

Which of the following is a primary difference between ectomycorrhizae and endomycorrhizae?

A) Endomycorrhizae have thicker, shorter hyphae than ectomycorrhizae.
B) Endomycorrhizae, but not ectomycorrhizae, form a dense sheath over the surface of the root.
C) Ectomycorrhizae do not penetrate root cells, whereas endomycorrhizae grow into invaginations of the root cell membranes.
D) Ectomycorrhizae are found in woody plant species; about 85% of plant families form ectomycorrhizae.