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'.

Ex Input:
Problem: the difference between simple and compound interest on rs . 1600 for one year at 10 % per annum reckoned half - yearly is ?
Options: a ) 8 , b ) 3 , c ) 9 , d ) 4 , e ) 2

Ex Output:
d

Ex Input:
Problem: rs 3600 is divided into two parts such that one part is put out at 3 % and the other at 5 % . if the annual interest earned from both the investments be rs 144 , find the first part .
Options: a ) s 4000 , b ) s 2800 , c ) s 1800 , d ) s 3500 , e ) s 3100

Ex Output:
c

Ex Input:
Problem: in an examination 35 % of the students passed and 546 failed . how many students appeared for the examination ?
Options: a ) a ) 540 , b ) b ) 400 , c ) c ) 700 , d ) d ) 650 , e ) e ) 840

Ex Output:
e