The molecule shown here is leucine, one of the amino acids that are the building blocks of proteins. The color key for the atoms is carbon (black), hydrogen (light gray), oxygen (red), and nitrogen (blue).

a. How many different elements are in a molecule of leucine?

b. How many carbon atoms are in a molecule of leucine?

c. Which element has the largest number of atoms in a leucine molecule?

d. What is the total number of atoms in a molecule of leucine?