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 man can row upstream at 26 kmph and downstream at 30 kmph , and then find the speed of the man in still water ? 
Options: a ) 29 , b ) 28 , c ) 30 , d ) 32 , e ) 23

Output: b


Input: Consider Input: Problem: a can do a piece of work in 80 days and b in 100 days . they work together for 20 days and then b goes away . in how many days will a finish the remaining work ? 
Options: a ) 33 days , b ) 44 days , c ) 55 days , d ) 42 days , e ) 32 days

Output: b


Input: Consider Input: Problem: worker a takes 8 hours to do a job . worker b takes 10 hours to do a job . how long should it take both a and b , working together to do same job 
Options: a ) 49 , b ) 249 , c ) 349 , d ) 449 , e ) none of these


Output: d