Explanation:

- Let's denote the original number as 10x + y, where x and y are the digits.

- We know the sum of the digits is 12: x + y = 12.

- When the digits are reversed, the number becomes greater by 18: 10y + x = 10x + y + 18.

- Simplifying the second equation: 9y - 9x = 18, which gives y - x = 2.

- From x + y = 12, substitute y = x + 2: x + (x + 2) = 12, leading to 2x + 2 = 12, so 2x = 10, and x = 5.

- Then y = 12 - x = 7.

- The difference between the digits is 7 - 5 = 2.

- Option 2: 2