The correct answer to this question is this one: they lacked oxygen. The earliest organisms were completely heterotrophic in nature because of the reason that they lacked oxygen. <span>A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. </span>
Answer:
May be Nutritional but no sure
<span>Protista and Eubacteria so the last one.</span>
Carbohydrates give energy to the body.
Hope this helps!!
