Explanation:

- Statement: Simple interest (SI) for 5 years equals 25% of the principal.

- This implies SI for 1 year = 25% of principal / 5 = 5% of principal.

- Determine SI equal to principal:

- We want SI to be 100% of the principal.

- If 5% of the principal is for 1 year, then to reach 100%, it will take:

$$

\text{Years} = \frac{100\%}{5\%} = 20 \text{ years}

$$

- Option Analysis:

- Option 1: 20 years – Correct, as derived from above.

- Option 2: 30 years – Excess, as only 20 years needed.

- Option 3: 26 years – Excess, as only 20 years needed.

- Option 4: 22 years – Slight overestimation than needed.

- Correct Answer: Option 1: 20 years