Since the maximum capacity of Mark's car is 20 gallons, so he can buy up to 20 gallons or even 20 gallons. Then

On the other hand, since it doesn't make sense for Mark to buy 0 gallons then he will buy more than 0 gallons. Then
![0Therefore, <strong>the most appropriate domain of the function is </strong>[tex]g\le20](https://img.qammunity.org/2023/formulas/mathematics/college/7e0fsz7pngape2g9vtb9xb2h4eybfz2nuf.png)
and the correct answer is C.