So that all animals can be classified and accounted for. This is also used in dichotomy analysis in order to find out the species of an invasive plant or animal
I would go with hypothesis because I never heard any of the other answers in Bio and a hypothesis is an educated guess so it means what you already know and it’s an observation (I hope this helped!!)
brain is the organ which does play a role in mechanical or chemical digestion
Answer: d- because a model is never exactly the same as the thing it represents