Question

which is not a model? a drawing of electrons in evenly distributed positive charge to represent an atom balls in a bowl of jelly to show how light moves through space a standard by which test results can be compared

Explanation:

A standard for comparing test results is a benchmark or reference - not a model. Balls in a bowl to show light movement is a physical model for light behavior. A drawing of electrons in evenly distributed positive charge is a model of an atom (like the plum - pudding model).

Answer:

A. a standard by which test results can be compared