Answer
A is III; B is II; C is I
Work Step by Step
We can see which graph is which by seeing where each graph crosses the y axis (this is the y intercept). All functions are in the form y=mx+b, so we know that the y-intercept will always be the thing being added to the x value. In the case of A, -3 is being added to x. Graph III is the only one with a y-intercept of -3, so we know that this is the match for A. For function B, the value for b is 1, so we know that it must be graph II, which has a y-intercept of 1. This means that C is Graph I.