Here's a problem to solve: The liver converts glucose to glycogen for storage. Why is this function considered a chemical change?

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

- A: because the conversion transforms solids to liquids
 
- B: because the conversion allows for less glucose in the liver
 
- C: because the conversion changes one substance to a new one
 
- D: because the conversion changes the shape of the liver cells
 