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: what is the minimum percentage increase in the mean of set f { - 4 , - 1 , 0 , 6 , 9 } if its two smallest elements are replaced with two different primes ? 
Options: a ) 25 % , b ) 50 % , c ) 75 % , d ) 100 % , e ) 200 %
Example Output: d

Example Input: Problem: find √ ? / 19 = 4 ? 
Options: a ) 76 , b ) 5776 , c ) 304 , d ) 1296 , e ) none
Example Output: b

Example Input: Problem: working alone , printers x , y , and z can do a certain printing job , consisting of a large number of pages , in 12 , 10 , and 20 hours , respectively . what is the ratio of the time it takes printer x to do the job , working alone at its rate , to the time it takes printers y and z to do the job , working together at their individual rates ? 
Options: a ) 5 / 3 , b ) 7 / 4 , c ) 9 / 5 , d ) 11 / 6 , e ) 13 / 7
Example Output:
c