The answer is B.
Animals do cellular respiration which requires the intake of oxygen and the output of carbon dioxide. In order for plants to do photosynthesis, they need carbon dioxide to be able to make oxygen for animals to breathe.
The correct answer to go in the blank would be ''laws''.
Answer:
Facilitated Diffusion
Explanation:
Some molecules can move down their concentration gradients by crossing to the lipid portion of the membrane directly,while others must pass through membrane protein s in a process called Facilitated Diffusion
I believe it would be sperm
