In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: what is the least whole number that should be added to 784839 if it is to be divisible by 10 ? 
Options: a ) 3 , b ) 2 , c ) 1 , d ) 5 , e ) 6
Example Output: c

Example Input: Problem: village x has a population of 72000 , which is decreasing at the rate of 1200 per year . village y has a population of 42000 , which is increasing at the rate of 800 per year . in how many years will the population of the two villages be equal ? 
Options: a ) 15 , b ) 19 , c ) 11 , d ) 18 , e ) 13
Example Output: a

Example Input: Problem: what is the units digit of 2222 ^ ( 333 ) * 3333 ^ ( 222 ) ? 
Options: a ) 0 , b ) 2 , c ) 4 , d ) 6 , e ) 8
Example Output:
e