Demonstrative pronoun is the answer.
I think the answer to this question is hypertonic to hypotonic as diffusion is the movement of water from a high to low concentration and hypertonic contains a high concentration of solutes and hypotonic contains a low concentration of solutes (the are opposites). Hope this makes sense
Answer:
B
Explanation:
The experimental drug has a direct effect on the dependent variable which is the presence of the headache.
Option C : oxygen and Option B: nutrients
