The correct option is C Centrifugation
Centrifugation is used to separate components of colloids based on difference in their densities.
Milk is a colloid, therefore it's components can be easily separated by centrifugation.
Filtration and sedimentation cannot be used, since the components of milk are not large enough to get filtered or settle down at bottom.
Separating funnel is used to separate the immiscible liquids that form separate layers because of density difference. Since the components of colloids do not settle down, therefore separate layers are not formed.