Correct answer: 25
Explanation:
The sequence is: 781, 806, 831, 781, 806, 831, ...
This is a repeating pattern and not a standard Arithmetic Progression.
However, if we consider only the first three terms: 781, 806, 831
Then: \[ 806 - 781 = 25,\quad 831 - 806 = 25 \] So, the common difference is 25