Batman and Robin were studying physical and chemical properties of matter. They determined that the mass of a sample was 50 grams. Which sentence best states how mass describes matter?

Question

$\begin{array}{1 1}\text{a. The mass of a substance is a way to measure the amount of matter it contains.} \\ \text{ b. Mass is a way to measure the force of gravity on a substance.} \\ \text{ c. The mass of a substance may change, based on its location.} \\ \text{ d. Mass is a chemical property of a substance. } \end{array}$