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: if 213 × 16 = 3408 , then 16 × 21.3 is equal to : 
Options: a ) 0.3408 , b ) 3.408 , c ) 34.08 , d ) 340.8 , e ) none of these
Example Output: d

Example Input: Problem: for the positive integers x , x + 2 , x + 4 , x + 7 , and x + 17 , the mean is how much greater than the median ? 
Options: a ) 0 , b ) 1 , c ) 2 , d ) 4 , e ) 7
Example Output: c

Example Input: Problem: at the end of year x , automobile installment credit accounted for 36 % of all outstanding consumer installment credit . at that time automobile finance companies extended $ 35 billion of credit , or 1 / 3 of the automobile installment credit . how many billion dollars of consumer installment credit was outstanding at that time ? 
Options: a ) 291.67 , b ) 105 , c ) 301.05 , d ) 288 , e ) 249.55
Example Output:
a