Answer:
The function's graphic is the one that is below the first one in th right.
Explanation:
If we want to know how much Chelsea earns for dogsitting her neighbours' dogs, we have to form a linear equation, that must have the following formula:

In this case, B is the constant value. We know Chelsea charges 12$ for dogsitting, and that doesn't depend on anything (B). But, if you want to Chelsea to walk your dog, then you'd to pay 2.50$ for each walk (X).

So, if Chelsea doesn't walk the neighbour's dog (x=0), she would be earning 12 dolars.

If she walks four times the dog, she would be earning:

Knowing these two values, we can graph the equation. When x=0, y=12, and when x=4, y=22
The function's graphic is the one that is remarked in the attachment.