Answer the following question given this paragraph: 

Density describes how much matter is in a certain amount of space. Substances that have more matter packed into a given space have higher densities. The water in a drinking glass has the same density as the water in a bathtub or swimming pool. All substances have characteristic densities, which does not depend on how much of a substance you have.


Q: What describes how much matter is in a certain amount of space?

 Choices:

- volume

- mass

- viscosity

- density

A:
density
