The correct option is C Surfactants form micelle above critical micelle concentration (CMC). CMC depends on temperature.
(A) Process of precipitating colloidal solution by using an electrolyte is called coagulation
(B) Since, molar mass of sol is much higher than true solutions, so magnitude of any colligative properties is smaller than true solutions.
(ΔTf)sol<(ΔTf)true solution
So, freezing point of solution is greater than the freezing point of true solution.
So, option (B) is correct.
(C) Micells are formed greater than or equal to CMC and above kraft temperature.
So option (C) is also correct.
(D) Micelles are associated colloids and not macromolecular colloids.