Task: Question Answering
Input (English): Problem: a survey was sent to 70 customers , 7 of whom responded . then the survey was redesigned and sent to another 63 customers , 9 of whom responded . by approximately what percent did the response rate increase from the original survey to the redesigned survey ? 
Options: a ) 2 % , b ) 6 % , c ) 4 % , d ) 28 % , e ) 63 %
Output (English): c