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 can do a piece of work in 4 hours ; b and c together can do it in 2 hours , while a and c together can do it in 2 hours . how long will b alone take to do it ? 
Options: a ) 12 , b ) 9 , c ) 8 , d ) 6 , e ) 4

Output: e


Input: Consider Input: Problem: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 5 km ? 
Options: a ) 2.0 , b ) 2.5 , c ) 3.0 , d ) 3.5 , e ) 4.0

Output: b


Input: Consider Input: Problem: on a trip , a cyclist averaged 8 miles per hour for the first 16 miles and 10 miles per hour for the remaining 16 miles . if the cyclist returned immediately via the same route and took a total of 6.8 hours for the round trip , what was the average speed ( in miles per hour ) for the return trip ? 
Options: a ) 9 , b ) 10 , c ) 11 , d ) 12 , e ) 13


Output: b