In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: the mean of 40 observations was 100 . it was found later that an observation 50 was wrongly taken as 75 the corrected new mean is 
Options: a ) 125.8 , b ) 102.8 , c ) 99.375 , d ) 100.52 , e ) 122
Example Output: c

Example Input: Problem: find out the square of a number which when doubled exceeds its one fifth by 9 ? 
Options: a ) 16 , b ) 25 , c ) 19 , d ) 26 , e ) 17
Example Output: b

Example Input: Problem: in a group of cows and hens , the number of legs are 16 more than twice the number of heads . the number of cows is : 
Options: a ) 5 , b ) 6 , c ) 7 , d ) 8 , e ) 12
Example Output:
d