To calculate the percent increase, you can use the formula:
\[ \text{Percent Increase} = \frac{\text{New Price} - \text{Original Price}}{\text{Original Price}} \times 100 \]
In this case, the original price is $20 and the new price is $25. Plugging in these values:
\[ \text{Percent Increase} = \frac{25 - 20}{20} \times 100 = \frac{5}{20} \times 100 = 0.25 \times 100 = 25% \]
So, the percent increase is D) 25%.