The current classification system is extremely dynamic. In 1753, Linnaeus classified all organisms into two kingdoms. Nearly a century later it was expanded to a three-kingdom system. Currently, we use a six-kingdom system for classification. Which statement best explains why the classification system keeps changing?

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

answer; synapse; i believe this is correct,plz check first good luck;