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

Example Input: Problem: a cylindrical cube of radius 12 cm contains water upto a depth of 20 cm . a spherical iron ball is dropped into the tub and thus the level of water is raised by 6.75 cm . the radius of the ball is :
Options: ['a ) 7 cm', 'b ) 8.5 cm', 'c ) 9 cm', 'd ) 9.5 cm', 'e ) none']
Example Output: c

Example Input: Problem: what is the smallest positive integer x , such that 1152 x is a perfect cube ?
Options: a ) 4 , b ) 6 , c ) 8 , d ) 12 , e ) 18
Example Output: d

Example Input: Problem: if the sum of a number and its square is 210 , what is the number ?
Options: a ) 16 , b ) 14 , c ) 25 , d ) 87 , e ) 171
Example Output:
b