Since you don't show the graph, all I can do is to tell you how to identify which function is parallel to the x-5y=8.
First let's rearrange the function.
x-5y=8
5y=x-8
y=1/5x-8/5.
Thus, it gives us the slope of the function, which is 1/5.
And the function that is parallel to the graph would have the SAME slope. Which is 1/5. So all you need to do is to find which function has the SAME SLOPE, in this case: 1/5.