The graph illustrates how pressure caused by a liquid changes with depth below the liquid surface. The gravitational field strength $g$ is $9.8\,\text{N kg}^{-1}$. What is the density of the liquid?
- A$200\,\text{kg m}^{-3}$
- B$820\,\text{kg m}^{-3}$
- C$2000\,\text{kg m}^{-3}$
- D$8200\,\text{kg m}^{-3}$