Why is the dam of a water reservoir thick at the bottom?

At shallow depth $h$,the pressure in the ocean is simply given by $P = P_0 + \rho gh$,in which $\rho$ is the density of water and $P_0$ is the air pressure. As we go deeper,the high pressure causes the water to compress and become denser. Which of the following sketches illustrates the correct dependence of the pressure on the depth $h$ ?

$A$ person of height $1.65 \,m$ is standing upright. The additional external force required by a blood vessel of length $1 \,cm$, diameter $1 \,mm$ at the feet to balance the pressure compared to a similar blood vessel in the head is (Density of blood $= 1.1 \times 10^3 \,kg \,m^{-3}$, $g = 10 \,ms^{-2}$) (in $\,N$)

What is the effect of pressure on the boiling point of water?

$A$ nurse measures the blood pressure of a seated patient to be $190 \,mm$ of $Hg$.

Two liquids of densities $\rho_1 = 1$ and $\rho_2 = 2$ are mixed in equal masses. What is the density of the resulting mixture?