6. Of all the macromolecules, proteins have the widest range of functions.Which characteristic of proteins makes them so diverse?
a) They are suspended in the phospholipid bilayer of cells' membranes.
b) They are essential for muscle contraction.
c) They have the greatest structural variety.
d) They transport other molecules.

The correct answer is acquired immunity. Basically, once you get them, your body develops the immunity to fight it off. Since the measles don't change, you will never be able to get them again because you got the immunity, or acquired it, the first time you had them. Many parents go as far as to give measles to siblings of infected children so as to have the kids go through it at a young age.