Answer:
C. 15%
Step-by-step explanation:
The percentage of the increase can be calculated using the following equation:
![(V_f-V_i)/(V_i)*100\text{ \%}](https://img.qammunity.org/2023/formulas/mathematics/college/1usyyes0r0zmxtmn7aslonej4vnqpmqcj6.png)
Where Vf is the final price of a gallon of gas and Vi is the initial price of a gallon of gas. So, replacing Vf by $2.25 and Vi by $1.95, we get that the percentage of increase is equal to:
![(2.25-1.95)/(1.95)*100\text{ \% = 15.38\%}](https://img.qammunity.org/2023/formulas/mathematics/college/d4pzk4vkwpo633reexhmtibjdv73t1hhxe.png)
Therefore, the answer is C. 15%