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: i flew my tiny seaplane to visit my mother . on the flight up , i flew at 110 mph . on the way home , i flew 90 mph . what was my average speed for the trip ? 
Options: a ) 198 mph , b ) 110 mph , c ) 88 mph , d ) 100 mph , e ) 99 mph

Ex Output:
d


Ex Input:
Problem: an seller earns an income of re 1 on the first day of his business . on every subsequent day , he earns an income which is just thrice of that made on the previous day . on the 20 th day of business , he earns an income of : 
Options: a ) 29 , b ) 57 , c ) 35 , d ) 20 , e ) 30

Ex Output:
b


Ex Input:
Problem: 66 cubic centimetres of silver is drawn into a wire 1 mm in diameter . the length of the wire in metres will be : 
Options: a ) 66 , b ) 84 , c ) 80 , d ) 72 , e ) 68

Ex Output:

b