Answer:
non-specific system
Explanation:
The non-specific immune system is the system that works 24 hours a day, 7 days a week and protects you, regardless of the organism you encounter. This system is composed of the general defenses of the organism that work continuously, creating barriers that protect the body from the entry of any pathogen or foreign substance. This system is composed of T cells, which are true killers of pathogens and which guarantee efficient and complete safety.
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:
I think the answer is D: Infrographic that shows carbon moving through ecosystems
