Which is not true about a direct proportion? a. its graph must be linear? b. its graph must have a slope of 0? c. its graph must have a constant slope? d. its graph must go through the origin

In the graph of a direct proportion, its graph shows a straight line graph or a linear graph that go through the origin. So that makes options A and options D correct. It's slope is also constant so therefore option C is correct, leaving us option B as the statement that is not true about direct proportion. Hope this answers your question.

Letter c i’d say