Knowing that she is already 75 years old, even though we don't know her health conditions, we can conclude that the vitamins might help her to avoid any deficiency related to minerals and vitamins, and it might also help her if she has an alimentary restriction meaning that she can't it a food that contains a needed vitamin or mineral.
Hope it helps,
Happy homework/ exam/ study!
I am not sure but I am guessing carbon and nitrogen :)
I believe that you're question is referring to homeostasis
Lichens are prominent on rocky shores.
This is true. There are a few websites online that talk about how it happens, I suggest looking them up.