First option.
Step-by-step explanation:
The equation of a line that passes through the origin (which is the point ), has the following form:
Where "m" is the slope of the line.
By definition, Proportional relationships have this form:
Where "k" is the Constant of proportionality.
Therefore, the graph of a Proportional relationship is a straight line that passes through the origin; then:
Observe the equations provided in the exercise's options.
In this case you can identify that the only equation that has the form explained before, is the first one:
And the Constant of proportionality is: