Explanation:

- Let’s assume the cost price (CP) is $100x$.

- The marked price (MP) is set such that 15% of MP equals 25% of CP.

- Equation: $0.15\times MP=0.25\times 100x$.

- Solution: $MP=\frac{25}{15}\times 100x=\frac{5}{3}\times 100x=166.67x$.

- A discount of 25% on $166.67x$ brings the selling price (SP) to 75% of MP.

- Calculation: $SP=0.75\times 166.67x=125x$.

- Profit = SP - CP = $125x-100x=25x$.

- Profit Percentage: $\frac{25x}{100x}\times 100=25$.

- The correct answer is Option 4: 25%.