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: the average of 13 numbers is 60 . average of the first 7 of them is 57 and that of the last 7 is 61 . find the 8 th number ?
Options: a ) 43 , b ) 30 , c ) 35 , d ) 45 , e ) 50

Ex Output:
a

Ex Input:
Problem: what is the greatest value of positive integer x such that 2 ^ x is a factor of 100 ^ 50 ?
Options: a ) 70 , b ) 80 , c ) 90 , d ) 100 , e ) 120

Ex Output:
d

Ex Input:
Problem: how many times digit 10 is used while writing numbers from 100 to 1000 ?
Options: a ) 100 , b ) 90 , c ) 85 , d ) 110 , e ) 120

Ex Output:
b