It's an inherently bad question because, as the other poster mentioned, the conditions aren't specified. All things being equal, I'd say an emulsion - but an emulsion can have very high viscosity that will prevent easy flow. Mayonnaise is an example. Foams like Coolwhip are kind of like emulsions, too, and they don't flow very well either.
Just a bad question all around, but emulsion seems the best option.