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'.

Ex Input:
Problem: if 20 typists can type 50 letters in 30 minutes , then how many letters will 40 typists working at the same rate complete in 1 hour ? 
Options: a ) 400 , b ) 500 , c ) 350 , d ) 250 , e ) 200

Ex Output:
a


Ex Input:
Problem: a man rows his boat 75 km downstream and 45 km upstream , taking 2 1 / 2 hours each time . find the speed of the stream ? 
Options: a ) 6 , b ) 7 , c ) 5 , d ) 8 , e ) 9

Ex Output:
a


Ex Input:
Problem: the h . c . f of two numbers is 11 and their l . c . m is 7700 . if one of the numbers is 275 , then the other is ? 
Options: a ) 288 , b ) 277 , c ) 308 , d ) 988 , e ) 112

Ex Output:

c