Which of the following colligative properties can provide molar mass of proteins (or polymers or colloids) with greater precision

The correct option is D Osmotic pressure

Osmotic pressure method is especially suitable for the determination of molecular masses of macromolecules such as protein & polymer because for these substances the value of other colligative properties such as elevation in boiling point or depression in freezing point are too small to be measured on the other hand osmotic pressure of such substances are measurable