Which one has the highest osmotic pressure?

$A$ $6 \%$ solution of urea is isotonic with

To have an osmotic pressure equal to a solution containing $9.2 \ g$ of glucose per liter,how many grams of glucose must be dissolved in $0.5 \ L$ of solution?

$3 \ mL$ of solution was made by dissolving $20 \ mg$ of protein at $0^{\circ} C$. The osmotic pressure of the resulting solution is $3.8 \ torr$. The molecular weight of the protein is approximately $(g/mol)$

If the osmotic pressure of cane sugar solution is $2.46 \ atm$ at $27^{\circ} C$,then what is the concentration (in $mol \ L^{-1}$) of the solution $(R=0.0821 \ L \ atm \ mol^{-1} \ K^{-1})$?

Which one of the following solutions of compounds shows the highest osmotic pressure? ($AB, AB_2$ and $A_2 B_3$ are ionic compounds)