The Major Different Between Class I Fusion Proteins and Class

The major different between class I fusion proteins and class II fusion proteins is that ….

A) class I protein mediate fusion at the plasma membrane and class II protein mediate fusion with the endosome membranes.
B) only class I proteins contain fusion peptides.
C) only class II proteins have a transmembrane domain.
D) only class I proteins undergo large conformation changes within the protein during entry.
E) class I proteins are found in unenveloped virus particles while class II proteins are found in enveloped particles.