Answer:
Option c:

Explanation:
The functional relationship between two variables can be easily found if it's represented as a line.
Larry's online calculator collects these points
(1, 5), (2, 9), (3, 13), (4, 17)
We can see there is a linear relation because every time the first component increases by 1, the second increases by 4.
The equation of a line is given by

Where m is the slope of the line and can be computed as

Where (a,b), (c,d) are two known points of the line. Let's use the first two points (1, 5), (2, 9)

We now know that

To compute the value of b, we use one of the points again, for example (1,5):

The relation is

We can test our results by using other points like (3,13)

And also

All points belong to the same function or rule
