Task: Question Answering
Input (English): Problem: a couple who own an appliance store discover that if they advertise a sales discount of 10 % on every item in the store , at the end of one month the number of total items sold increases 25 % . their gross income from sales for one month increases by what percent ? 
Options: a ) 5 % , b ) 7.5 % , c ) 10 % , d ) 12.5 % , e ) 15 %
Output (English): d