The answer is A!
Ron is showing an invalid experimental placebo in this experiment due to the positive response.
goodluck, :)
Answer:
1. Providing structure --> Collagen makes skin strong yet flexible.
2. Maintaining homeostasis --> Insulin controls the concentration of sugar in the blood.
3. Fighting Disease --> IgA prevents the buildup of viruses and bacteria in the gut.
4. regulating chemical reactions --> Pepsin works in the stomach to speed up the breakdown of food.
Digesting a sandwich
because your stomach acids break down the food so it can be digested and what not
