Correct option is B
Total no of person = 10
Let the total expenses = x
Then total expanses = x/10
The total people opted out = 2
Then expense on each person = x/8
Therefore, required percentage = ( x/8- x/10 )/(x/10)×100
=((5x-4x)/40 )/(x/10)×100
=(x/40 )/(x/10)×100=25%