Task: Question Answering
Input (English): Problem: the annual interest rate earned by an investment increased by 6 percent from last year to this year . if the annual interest rate earned by the investment this year was 15.90 percent , what was the annual interest rate last year ? 
Options: a ) 20 % , b ) 18 % , c ) 16 % , d ) 25 % , e ) 15 %
Output (English): e