Two solutions which have the same osmotic pressure at a given temperature are said to be isotonic in nature. The osmotic pressure of a given solution is given by the formula

π = CRT = n/VRT

Where π is the osmotic pressure of the solution, C is the concentration, the moles of solute per volume of solvent and T is the temperature, with R being universal gas constant. Osmotic pressure is a colligative property, hence it depends on the concentration of the solute in the solution and not the identity of either two. Hence the solvent and solute may or may not be the same.

Hence the correct answers are (ii) and (iii).