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: a man can row upstream at 5 kmph and downstream at 25 kmph , and then find the speed of the man in still water ? 
Options: a ) 15 , b ) 77 , c ) 30 , d ) 88 , e ) 34
Example Output: a

Example Input: Problem: a car gets 40 kilometers per gallon of gasoline . how many gallons of gasoline would the car need to travel 210 kilometers ? 
Options: a ) 8.25 gallons , b ) 7.5 gallons , c ) 6.55 gallons , d ) 5.25 gallons , e ) 4.5 gallons
Example Output: d

Example Input: Problem: the h . c . f of two numbers is 13 and their l . c . m is 2200 . if one of the numbers is 286 , then the other is ? 
Options: a ) 85 , b ) 90 , c ) 95 , d ) 100 , e ) 105
Example Output:
d