Answer:
The correct option is 3.
Step-by-step explanation:
It is given that the quantities of blue and green paints used for each mix and connected them using a line segment, as shown in the graph below:
The line have two end points A(1,2) and B(9,14).
Domain is the set of inputs. In a graph all the values of x for which the graph is defined, are domain of the function.
The line is defined from x=1 to x=9. So, the domain of the function lies between 1 to 9 (inclusive).

Therefore, option 3 is correct.
Yes because you are basically taking what you are giving in the first place
A proportional relationship would look like y=mx (no y-intercept).
The formula for temperature Fahrenheit involves an offset (y-intercept); this is one reason I claim that the relationship in question is NOT proportional.