$A$ wide vessel with a small hole at the bottom is filled with two liquids. The density and height of one liquid are $\rho_1$ and $h_1$ and that of the other are $\rho_2$ and $h_2$ $(\rho_1 > \rho_2)$. The velocity of the liquid coming out of the hole is:

• A
  $v = \sqrt{2g(h_1 + h_2)}$
• B
  $v = \sqrt{2g(h_1\rho_1 + h_2\rho_2) / (\rho_1 + \rho_2)}$
• C
  $v = \sqrt{2g(h_1 + \frac{h_2\rho_2}{\rho_1})}$
• D
  $v = \sqrt{2g(\frac{h_1\rho_1}{\rho_2} + h_2)}$