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: find the length of the wire required to go 15 times round a square field containing 69696 m 2 . 
Options: a ) 15840 , b ) 15848 , c ) 15828 , d ) 27892 , e ) 22892
Example Output: a

Example Input: Problem: a worker earns $ 20 on the first day and spends $ 15 on the second day . the worker earns $ 20 on the third day and spends $ 15 on the fourth day . if this pattern continues , on which day will the worker first reach a net total of $ 90 ? 
Options: a ) 28 , b ) 29 , c ) 31 , d ) 34 , e ) 36
Example Output: b

Example Input: Problem: some persons can do a piece of work in 12 days . two times the number of such persons will do half of that work in 
Options: a ) 9 , b ) 8 , c ) 4 , d ) 3 , e ) 1
Example Output:
d