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: the number 152 is equal to the sum of the cubes of two integers . what is the product of those integers ?
Options: a ) 8 , b ) 15 , c ) 21 , d ) 27 , e ) 39
Example Output: b

Example Input: Problem: if ( a - b - c + d = 13 ) and ( a + b - c - d = 9 ) , what is the value of ( b - d ) ^ 2 ?
Options: a ) 4 . , b ) 8 . , c ) 12 . , d ) 16 . , e ) 64 .
Example Output: a

Example Input: Problem: given f ( x ) = 2 x 3 , for what value of x does 2 * [ f ( x ) ] 11 = f ( x 2 ) ?
Options: a ) 2 , b ) 3 , c ) 4 , d ) 5 , e ) 6
Example Output:
d