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

Example Input: Problem: if 8 people take an hour to complete a piece of work , then how long should 16 people will take to complete the same piece of work ? 
Options: a ) 15 min , b ) 30 min , c ) 26 min , d ) 28 min , e ) 18 min
Example Output: b

Example Input: Problem: a and b can do a piece of work in 3 days , b and c in 4 days , c and a in 6 days . how long will c take to do it ? 
Options: a ) 33 , b ) 77 , c ) 24 , d ) 55 , e ) 71
Example Output: c

Example Input: Problem: factory x ' s bulbs work for over 5000 hours in 78 % of cases , whereas factory y ' s bulbs work for over 5000 hours in 65 % of cases . it is known that factory x supplies 90 % of the total bulbs available . what is the chance that a purchased bulb will work for longer than 5000 hours ? 
Options: a ) 76.4 % , b ) 76.7 % , c ) 77.4 % , d ) 75 % , e ) 73.9 %
Example Output:
b