Explanation:

To find the percent increase:

- We start with 90 and it becomes 117.

- The increase is \(117 - 90 = 27\).

- To find the percentage increase, use the formula: \((\frac{\text{increase}}{\text{original number}}) \times 100\).

- This gives \((\frac{27}{90}) \times 100 = 30\).

Let's evaluate the options:

- Option 1: 20 - This would mean an increase of \(18\) (since \((\frac{20}{100}) \times 90 = 18\)), but 90 + 18 is not 117.

- Option 2: 30 - This is the correct one since \((\frac{30}{100}) \times 90 = 27\), and 90 + 27 = 117.

- Option 3: 15 - This would mean an increase of \(13.5\) \((\frac{15}{100}) \times 90\), which doesn’t add up.

- Option 4: 25 - An increase of \(22.5\) \((\frac{25}{100}) \times 90\) also doesn’t suffice.

The correct answer is:

- Option 2: 30