Here's a problem to solve: The elements carbon, hydrogen, and oxygen are parts of many different compounds. Which explains why these three elements can make so many different compounds?

Among the 4 following options, which is the correct answer?

- A: They can be solids, liquids, or gases.
 
- B: They come in different sizes and shapes.
 
- C: They combine in different numbers and ratios.
 
- D: They can be a proton, a neutron, or an electron.
 