Why give me reasons?

Answer:
We can test for proportionality on a graph by looking for various properties.
- A proportional graph will always go through the origin (0,0)
- A proportional graph will be a straight line.
- If you list points (ordered pairs) from a graph, you can create ratios and see if they are constant (equal).
Step-by-step explanation: Check for these things when looking at the graph, and write down what the graphs lack.
:)