One Major Difference Between Ectomycorrhizae and Arbuscular Mycorrhizae Is

One major difference between ectomycorrhizae and arbuscular mycorrhizae is

A) ectomycorrhizae are parasitic on plant roots while arbuscular mycorrhizae are not.
B) ectomycorrhizae do not penetrate plant roots; arbuscular mycorrhizae penetrate plant roots.
C) ectomycorrhizae are more common on plant roots than arbuscular mycorrhizae.
D) ectomycorrhizae form mutualisms while arbuscular mycorrhizae are parasitic.