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: the length of the bridge , which a train 140 metres long and travelling at 45 km / hr can cross in 30 seconds , is : 
Options: a ) 200 m , b ) 235 m , c ) 245 m , d ) 250 m , e ) 270 m
Example Output: b

Example Input: Problem: a can do a piece of work 60 days . b can do work in 20 days . in how many days they will complete the work together ? 
Options: a ) 12 days , b ) 16 days , c ) 15 days , d ) 17 days , e ) 18 days
Example Output: c

Example Input: Problem: the l . c . m of 22 , 54 , 108 , 135 and 198 is 
Options: a ) 5942 , b ) 2887 , c ) 5940 , d ) 2888 , e ) 28881
Example Output:
c