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 copy machine , working at a constant rate , makes 40 copies per minute . a second copy machine , working at a constant rate , makes 55 copies per minute . working together at their respective rates , how many copies do the two machines make in half an hour ?
Options: a ) 90 , b ) 2,700 , c ) 4,500 , d ) 5,400 , e ) 2,850

Output: e

Input: Consider Input: Problem: two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 1.75 km and 1.25 km respectively . the time taken by the slower train to cross the faster train in seconds is ?
Options: a ) 12 , b ) 72 , c ) 48 , d ) 99 , e ) 11
Output: b