The average osmotic pressure of human blood is $7.8$ bar at ${37}^0\mathrm{C}$ . What is the concentration of an aqueous $\mathrm{NaCl}$ solution that could be used in the blood stream ?

Among $0.1 \mathrm{M}$ solutions of urea, ${\mathrm{Na}}_3{\mathrm{PO}}_4$ and ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$:

$\left(\mathrm{a}\right)$ The vapour pressure and freezing point are the lowest for urea

$\left(\mathrm{b}\right)$ The vapour pressure and freezing point are the highest for urea

$\left(\mathrm{c}\right)$ The elevation in boiling point is the highest for ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$

$\left(\mathrm{d}\right)$ The depression in freezing point is the highest for ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$