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: what annual installment will discharge a debt of rs . 1428 due in 3 years at 12 % simple interest ?
Options: a ) 315 , b ) 345 , c ) 425 , d ) 335 , e ) none of them

Ex Output:
c

Ex Input:
Problem: calculate how many seconds it will take for 4 bells to toll together again , given that they begin to toll together respectively at the intervals of 9 , 10 , 14 and 18 seconds . ?
Options: a ) 636 , b ) 631 , c ) 633 , d ) 610 , e ) 630

Ex Output:
e

Ex Input:
Problem: money invested at x % , compounded annually , triples in value in approximately every 112 / x years . if $ 2500 is invested at a rate of 8 % , compounded annually , what will be its approximate worth in 28 years ?
Options: a ) $ 3,750 , b ) $ 5,600 , c ) $ 8,100 , d ) $ 15,000 , e ) $ 22,500

Ex Output:
e