Which infectious agents are the most similar? Why?

List major types of infectious agents

There are five major types of infectious agents: bacteria, viruses, fungi, protozoa, and helminths. In addition, a new class of infectious agents, the prions, has recently been recognized.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands