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'.

Ex Input:
Problem: find the smallest positive integer n such that 11 n - 1 is divisible by 105 . 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7

Ex Output:
d


Ex Input:
Problem: a box contains 8 apples , 7 of which are red . an apple is drawn from the box and its color is noted before it is eaten . this is done a total of n times , and the probability that a red apple is drawn each time is less than 0.5 . what is the smallest possible value of n ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7

Ex Output:
c


Ex Input:
Problem: in a mixture of 45 litres the ratio of milk to water is 4 : 1 . additional 9 litres of water is added to the mixture . find the ratio of milk to water in the resulting mixture . 
Options: a ) 2 / 1 , b ) 4 / 1 , c ) 2 / 3 , d ) 3 / 4 , e ) 3 / 2

Ex Output:

a