Answer:
If it's directly proportional it should pass through the origin (0,0)
However, as one variable increases the other variable should, if the graph is proportional.
For example, if you double one variable, the other variable should also doubles.
E.g. As current increases, the voltage also increases : 2A to 2V but 4A to 4V.
Answer - It should be a straight (or linear) line passing through the origin.
Hope this helps!