$A$ cylindrical vessel of base radius $R$ and height $H$ has a narrow neck of height $h$ and radius $r$ at one end (see figure). The vessel is filled with water (density $\rho_w$) and its neck is filled with immiscible oil (density $\rho_0$). Then,the pressure at

• A
  $M$ is $g(h \rho_0 + H \rho_w)$
• B
  $N$ is $g(h \rho_0 + H \rho_w) \frac{r^2}{R^2}$
• C
  $M$ is $g H \rho_w$
• D
  $N$ is $g \frac{\rho_w H R^2 + \rho_0 h r^2}{R^2 + r^2}$