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'.

Ex Input:
Problem: the product of a and b is equal to 12 more than twice the sum of a and b . if b = 10 , what is the value of b - a ? 
Options: a ) 2 , b ) 5 , c ) 7 , d ) 6 , e ) 35

Ex Output:
d


Ex Input:
Problem: when processing flower - nectar into honey bees ' extract , a considerable amount of water gets reduced . how much flower - nectar must be processed to yield 1 kg of honey , if nectar contains 50 % water , and the honey obtained from this nectar contains 40 % water ? 
Options: a ) 1.2 kg , b ) 1.5 kg , c ) 1.7 kg , d ) 1.9 kg , e ) none of these

Ex Output:
a


Ex Input:
Problem: how many 4 digit numbers have no repeat digits , do not contain zero , and have a sum of digits d equal to 28 ? 
Options: a ) 14 , b ) 24 , c ) 28 , d ) 48 , e ) 96

Ex Output:

d