$\begin{array}{1 1} \text{A.mass times volume.} \\ \text{ B.mass divided by volume.} \\ \text{ C.mass plus volume.} \\ \text{ D.volume divided by mass.} \end{array}$
The density of a substance is the relationship between the mass of the substance and how much space it takes up (volume). The mass of atoms, their size, and how they are arranged determine the density of a substance.So, $density=\frac{mass}{volume}$.