The correct statement(s) related to colloids is(are)

For each option we recall standard definitions and properties of colloids and compare them with the statements.

Option A
Peptization is the conversion of a freshly precipitated solid into a colloidal sol by adding a suitable electrolyte. The opposite process, i.e. the precipitation of an existing colloidal sol by an electrolyte, is called coagulation or flocculation. Hence the statement is wrong.

Option B
Depression in freezing point ($$\Delta T_f$$) is a colligative property and is proportional to the number of solute particles present. In a true solution the solute consists of small molecules/ions, so the particle count (and therefore $$\Delta T_f$$) is large. In a colloidal sol each “particle” is an aggregate of many molecules, so the particle count per unit mass/concentration is much smaller, giving a much smaller $$\Delta T_f$$. Therefore the freezing temperature of a colloidal sol is closer to that of pure solvent (i.e. higher) than that of an equally concentrated true solution. Hence the statement is correct.

Option C
Surfactant molecules aggregate to form micelles only when their concentration exceeds the critical micelle concentration (CMC). The CMC itself is temperature-dependent; in particular micellisation occurs only above the Kraft temperature. Hence this statement is correct.

Option D
Micelles are formed by the association of many small surfactant ions or molecules, so they belong to the category of multimolecular (or associated) colloids, not macromolecular colloids (which consist of single giant molecules such as proteins, starch, rubber etc.). Therefore the statement is wrong.

Thus the correct statements are:
Option B (colloidal solution freezes at higher temperature than the true solution of the same concentration) and Option C (surfactants form micelles above CMC, and CMC depends on temperature).

Answer: Option B, Option C.