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: two trains 140 m and 160 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks . the time ( in seconds ) which they take to cross each other , is : 
Options: a ) 9 , b ) 9.6 , c ) 10 , d ) 10.8 , e ) 7
Example Output: d

Example Input: Problem: a car takes 6 hours to cover a distance of 504 km . how much should the speed in kmph be maintained to cover the same direction in 3 / 2 th of the previous time ? 
Options: a ) 48 kmph , b ) 50 kmph , c ) 52 kmph , d ) 56 kmph , e ) 60 kmph
Example Output: d

Example Input: Problem: a can do a work in 4 days . b can do the same work in 6 days . both a & b together will finish the work and they got $ 1000 from that work . find their shares ? 
Options: a ) 600,400 , b ) 500,500 , c ) 300,700 , d ) 800,200 , e ) 550,450
Example Output:
a