PLEASE HELP ME i will mark you brainless

1.  devloped

2. highest- USA lowest- austrailia

3. cause devloped contries have more tech and machinces that create carbon dioxide (like cars)

4. im not sure but one reason could be they are super eco-friendly and they dont have/use as many cars

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

it is either c or d and i know for sure it is not a or b