Task: Question Answering
Input (English): Problem: simple interest on a certain sum at a certain annual rate of interest is 1 / 9 of the sum . if the numbers representing rate percent and time in years be equal , then the rate of interest is : 
Options: a ) 5 , b ) 8 , c ) 3 1 / 3 , d ) 2 2 / 3 , e ) none of these
Output (English): c