The correct answer is option B, Paleozoic
In the Cambrian period of Paleozoic era of geological time period, most of the modern animals appear. Chordates were the first animal phylum that appeared during this time period along with several indistinct animal species such as Archaeocyatha, brachiopods, trilobite, pirapulid, sponges etc. The prokaryotes, protists, fungi and algae that appered during this era continues to modification and development till today
