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 first seven prime numbers which are between 30 and 70 is 
Options: a ) 35.4 , b ) 42 , c ) 44.4 , d ) 57 , e ) 67

Ex Output:
c


Ex Input:
Problem: a positive number x is multiplied by 7 , and this product is then divided by 3 . if the positive square root of the result of these two operations equals x , what is the value of x ? 
Options: a ) 7 / 3 , b ) 3 / 2 , c ) 4 / 3 , d ) 2 / 3 , e ) 1 / 2

Ex Output:
a


Ex Input:
Problem: find 4 + 7 + 10 + 13 + 16 + . . . up to 20 terms 
Options: a ) 650 , b ) 640 , c ) 630 , d ) 620 , e ) 610

Ex Output:

a