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: there are 17 stations between hyderabad and bangalore . how many second class tickets have to be printed , so that a passenger can travel from any station to any other station ? 
Options: a ) 156 , b ) 167 , c ) 157 , d ) 342 , e ) 380
Example Output: d

Example Input: Problem: if the wheel is 14 cm then the number of revolutions to cover a distance of 968 cm is ? 
Options: a ) a ) 15 , b ) b ) 10 , c ) c ) 14 , d ) d ) 12 , e ) e ) 11
Example Output: e

Example Input: Problem: two trains , one from howrah to patna and the other from patna to howrah , start simultaneously . after they meet , the trains reach their destinations after 25 hours and 16 hours respectively . the ratio of their speeds is ? 
Options: a ) 4 : 6 , b ) 4 : 3 , c ) 4 : 9 , d ) 4 : 5 , e ) 4 : 2
Example Output:
d