1. **State the problem:** We need to find the percentage increase when a company's sales increase from 250 to 300. 2. **Formula for percentage increase:** $$\text{Percentage Increase} = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100\%$$ 3. **Apply the values:** $$\frac{300 - 250}{250} \times 100\% = \frac{50}{250} \times 100\%$$ 4. **Simplify the fraction:** $$\frac{50}{250} = 0.2$$ 5. **Calculate the percentage:** $$0.2 \times 100\% = 20\%$$ 6. **Conclusion:** The percentage increase in sales is **20%**. Therefore, the correct answer is 20%.