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!
:)
Answer:
here is your Answer.
Explanation:
Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants .
One is were you bang someone else to reproduce and the other is where you bang yourself to reproduce
Answer:
<h2><u><em>
Upon reinfection, the memory cells will immediately differentiate into plasma cells and CTLs without input from APCs or TH cells.</em></u></h2>
Explanation:
<h3>Hope i helped (<em>Tell me the results in the comments below pls</em>) Good Luck!</h3>
