you can't go with one third becouse it is not listed you have to choose one.
I would go with 50% cos if we have to of 25% the odds would be one third so the aswers would be a )25% b) 50% c )60% so i choose 50% becouse you have 50% chances to be either 25% or 60% i might be wrong though
good riddle
im gold btw
or it could be 25% becouse you have 4 posible answers even though two of them are the same