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: if a is a positive integer , and if the units digit of a ^ 2 is 9 and the units digit of ( a + 1 ) ^ 2 is 4 , what is the units x digit of ( a + 2 ) ^ 2 ? 
Options: a ) 1 , b ) 3 , c ) 5 , d ) 6 , e ) c . 14

Ex Output:
a


Ex Input:
Problem: given f ( x ) = 3 x – 5 , for what value of x does 2 * [ f ( x ) ] – 10 = f ( x – 2 ) ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5

Ex Output:
c


Ex Input:
Problem: if 4 xz + yw = 6 and xw + yz = 12 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ? 
Options: a ) 9 . , b ) 30 . , c ) 15 . , d ) 16 . , e ) 18 .

Ex Output:

b