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: 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: a can do a piece of work in 12 days . he worked for 15 days and then b completed the remaining work in 10 days . both of them together will finish it in . 
Options: a ) 12 1 / 2 days , b ) 10 1 / 2 days , c ) 12 1 / 3 days , d ) 10 1 / 3 days , e ) 11 1 / 2 days

Ex Output:
a


Ex Input:
Problem: in a garden , 26 trees are planted at equal distances along a yard 600 metres long , one tree being at each end of the yard . what is the distance between two consecutive trees ? 
Options: a ) 10 , b ) 8 , c ) 12 , d ) 24 , e ) 16

Ex Output:

d