Correct choice is (c) 60- 70℃
To elaborate: Homogenization temperatures normally applied are 60 – 70°C, depending on the product. Processing at temperatures conducive to the partial solidification of milk fat (i.e. 30 – 35°C) results in incomplete dispersion of the fat phase. Homogenization is most efficient when the fat phase is in a liquid state and in concentrations normal to milk.