From this we can conclude that the human digestive system does not produce enzymes that can break down cellulose. The correct option among all the options that are given in the question is the fourth option or the last option. I hope that this is the answer that has come to your desired help.
Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
:)
➜ Fission (binary and multiple), regeneration and fragmentation are considered as methods of asexual reproduction because all of them involve only one parent and gametes are not formed in them. New individuals produced after cell division are always genetically identical or clone to their parents.
