Explanation:

- Simple Interest (SI) and Compound Interest (CI) are calculated on the principal amount.

- Both SI and CI are based on the same nominal rate and for 2 years.

- Formula for SI = Principal × Rate × Time / 100.

- Formula for CI = Principal × (1 + Rate/100)^Time - Principal.

- Difference between CI and SI given is Rs100.

- Let's denote the rate of interest as R.

$$

\text{CI - SI} = 2500 \times \left(1 + \frac{R}{100}\right)^2 - 2500 - \left(2500 \times \frac{R \times 2}{100}\right) = 100

$$

- Solve the above equation to find R.

- After calculation, R is found to be 20%.

- Therefore, the correct option is:

- Option 3: 20%