The correct option is B Cornflakes in milk
The filtration method is used for separating insoluble solid particles from the liquid. But the mixture of two liquids, such as oil in water cannot be separated by this method.
Also, salt in water, and sugar in milk, can not be separated by filtration, as salt is soluble in water, and sugar is soluble in milk.
So, cornflakes in milk can only be separated by filtration.