If a mixture looks smooth and the same throughout it is probably what

             If a mixture looks smooth and the same throughout it is probably Homogeneous.

Explanation:
                   Mixture is the combination of different compounds which are unreactive to each other.

Mixture are classified as ...

Solutions; in which the mixed compounds are thoroughly mixed and cannot be distinguished from each other and are said to be homogeneous. In solutions the size of solute is very small (i.e. Less than 1 nm).

Colloids; in which the solute is homogeneous visually but heterogeneous microscopically. The size of particles in this case is between 1 nm to 1 μm.

Suspensions; in which the mixture is heterogeneous, the particle size is greater than 1 μm and settles down (precipitation) under the influence of gravity.

D. most models represent a real world object in a simpler way