At constant temperature the osmotic pressure of a solution is

The osmotic pressure (p) of a solution at constant temperature is directly proportional to its concentration C, according to Vant Hoff Boyles Law (i.e., moles per litre)
$\mathrm{C}=\frac{\mathrm{n}}{\mathrm{v}}$
where $\mathrm{n}$ represents in volume V litres of solution, the number of moles of solute present.  So osmatic pressure depends on molar mass.

So, required option is A) directly proportional to the concentration