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: at a particular graduation party with 300 guests , 70 % of the guests brought gifts , and 40 % of the female guests brought gifts . if 30 males did not bring gifts to the party , how many females did bring gifts ?
Options: a ) 18 , b ) 28 , c ) 40 , d ) 68 , e ) 70

Ex Output:
c

Ex Input:
Problem: mary works in a restaurant a maximum of 70 hours . for the first 20 hours , she is paid $ 8 per hour . for each overtime hour , she is paid at a rate which is 25 % higher than her regular rate . how much mary can earn in a week ?
Options: a ) 600 , b ) 620 , c ) 660 , d ) 320 , e ) 400

Ex Output:
c

Ex Input:
Problem: in what ratio must water be mixed with milk to gain 16 2 / 3 % on selling the mixture at cost price ?
Options: a ) 1 : 9 , b ) 1 : 1 , c ) 1 : 2 , d ) 1 : 6 , e ) 1 : 5

Ex Output:
d