Answer:
your answer will be A
Step-by-step explanation:
^_^
It's B, because of the definition of a function.
Answer:
Third option
m = 2.25
Step-by-step explanation:
The slope of the function is equal to its rate of change between two points.
For example, for a couple of points 
The slope is:

In this problem we have the following points
1.(2, 8.50) , 2. (5, 15.25), 3. (8, 22.00) , 4. (12, 31.00)
We calculate the slope between the first two points

We calculate the slope between the points 3 and 4

We calculate the slope between the points 2 and 3

The slope is always the same. Therefore m is constant and the fution is a line of slope m = 2.25