If all of history were collapsed into a period of one year , when would bacterial life appear?

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

i think it’s c but i might be wrong. if i am let me know! have a good rest of your day as well!