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'.

Input: Consider Input: Problem: a train is 410 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 ) 44 seconds , c ) 40 seconds , d ) 50 seconds , e ) none of these

Output: b


Input: Consider Input: Problem: two cars a and b start from boston and new york respectively simultaneously and travel towards each other at constant speeds along the same route . after meeting at a point between boston and new york the two cars a and b proceed to their respective destinations of new york and boston . car a reaches new york 10 minutes after the two cars have met and car b reaches boston 90 minutes after they have met . how long did car a take to cover the distance between boston and new york ? 
Options: a ) 1 hour , b ) 1 hour 10 minutes , c ) 2 hours 30 minutes , d ) 50 minutes , e ) 2 hours 10 minutes

Output: d


Input: Consider Input: Problem: a man can do a piece of work in 10 days , but with the help of his son , he can do it in 4 days . in what time can the son do it alone ? 
Options: a ) 13 / 2 , b ) 17 / 3 , c ) 15 / 2 , d ) 20 / 3 , e ) 9


Output: d