Answer: non-proportional
The diagonal line does not go through the origin (0,0). In other words, the y intercept is not 0. Instead, the y intercept is 1.
The y intercept must be 0 for a proportional relationship to be possible because the general template is y = k*x, where k is some fixed number. Example: y = 9x is a proportional relationship in which y is 9 times larger than x.