The blood pressure in humans is greater at the feet , than at the brain.

Pressure of liquid at any point is proportional to height and density of liquid and acceleration due to gravity.

The blood pressure in humans is greater at the feet than at the brain.

Because pressure of fluid depends on height of fluid coloumn, density and acceleration due to gravity.

Considering blood in human body as static fluid.

We can have pressure at brain is ${\text{P}}_1$  and pressure at feet is equal to ${\text{P}}_2$ .

Using formula ${\text{P}}_{\text{2}}-{\text{P}}_1=h\text{ρg}$

$\rho$  of blood $=1060{\text{kg/m}}^{\text{3}}$

$\text{g}=9.8\text{0}{\text{m/s}}^{\text{2}}$

H = 1.8 m

${\text{P}}_2-{\text{P}}_1=1060\times 9.8\times 1.8$

Pressure difference between = 14 cm of Hg.

Brain & feet is nearly.

So we get both A & R are true and R is correct explanation for A