In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Ex Input:
Problem: a larger cube has 64 cubic inch as a volume and in the cube there are 64 smaller cubes such that their volume is 1 cubic inch . what is the difference between the surface areas ' sum of the 64 smaller cubes and the surface area of the larger cube , in square inch ?
Options: a ) 54 , b ) 64 , c ) 81 , d ) 288 , e ) 120

Ex Output:
d

Ex Input:
Problem: the diameter of a circle is 4 / . find the circumference of the circle .
Options: ['a ) 8', 'b ) 4 ', 'c ) 4', 'd ) 6', 'e ) 5']

Ex Output:
a

Ex Input:
Problem: if n is the smallest integer such that 108 times n is the square of an integer , what is the value of n ?
Options: a ) 2 , b ) 3 , c ) 6 , d ) 12 , e ) 24

Ex Output:
a