>>120565428A sauce implies viscosity. If the cereal can float in it, be suspended in it, rather than be coated by it, then it is not a sauce. And a broth implies it is water, distilled into new form by the simmering and dissolution of meat, vegetables, or some form of protein to create said broth. But milk is not initially water; it is produced internally within a mammal, and although it can be simmered in the pasteurization process, no foreign proteins are introduced in that sequence of events.
I tell you sir, if milk in cereal must be one of the three choices you've presented, I tell you it can only be a beverage. Now release this man's wife.