Answer:
The answer is D.
Explanation:
It occurs continuously in the cells of all organisms and often involves an exchange of gases. There are 2 types of cells, 1 is Eukaryotic, which holds a nucleus, and the 2nd is Prokaryotic, which do not. Prokaryotes are single-celled organisms.
B, as far as we know humans aren't from space
.............................b
