In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: john makes $ 60 a week from his job . he earns a raise and nowmakes $ 70 a week . what is the % increase ? 
Options: a ) 16 % , b ) 16.66 % , c ) 17 % , d ) 17.2 % , e ) 18 %
Example Output: b

Example Input: Problem: a particular library has 75 books in a special collection , all of which were in the library at the beginning of the month . these book are occasionally loaned out through an inter - library program . if , by the end of the month , 60 percent of books that were loaned out are returned and there are 65 books in the special collection at that time , how many books of the special collection were loaned out during that month ? 
Options: a ) 20 , b ) 25 , c ) 35 , d ) 40 , e ) 55
Example Output: b

Example Input: Problem: calculate how many seconds it eill take for 4 bells to toll together again , given that they begin to toll together respectively at the intervals of 5 , 8 , 11 and 15 seconds . ? 
Options: a ) 1310 , b ) 1320 , c ) 1322 , d ) 1323 , e ) 1312
Example Output:
b