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: a can do a piece of work in 4 hours ; b and c together can do it in 3 hours , which a and c together can do it in 2 hours . how long will b alone take to do it ? 
Options: a ) 15 hours , b ) 14 hours , c ) 12 hours , d ) 74 hours , e ) 79 hours
Example Output: c

Example Input: Problem: a train is 360 meter long is running at a speed of 45 km / hour . in what time will it pass a bridge of 140 meter length . 
Options: a ) 20 seconds , b ) 27 seconds , c ) 30 seconds , d ) 40 seconds , e ) 50 seconds
Example Output: d

Example Input: Problem: danny and steve are running towards each other , each one from his own house . danny can reach steve ' s house in 33 minutes of running , which is half the time it takes steve to reach danny ' s house . if the two started to run at the same time , how much time longer will it take steve to reach the halfway point between their houses than danny to reach the halfway point between their houses ? 
Options: a ) 16.5 minutes , b ) 33 minutes , c ) 49.5 minutes , d ) 66 minutes , e ) 99 minutes
Example Output:
a