The density of graphite is:

Density is defined as the mass-by-volume ratio. Its unit will be $\mathrm{g}/{\mathrm{cm}}^3$.

Graphite is an allotrope of carbon. A carbon atom in its structure uses only 3 of its electrons to bond with three other atoms. So carbon is $s{p}^2$ hybridized in graphite and its one free electron makes it a good electrical conductor

Graphite is used in pencils and lubricants. It is a strong conductor of heat and energy. In electrical devices such as electrodes, batteries and solar panels, its high conductivity is useful.

According to experimental calculations, the density of graphite is around $2.66 \mathrm{g}/{\mathrm{cm}}^3$. So the correct option is B.