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: the radius of a sphere is increased by 10 % . the surface area increases by ? 
Options: ['a ) 21 %', 'b ) 31 %', 'c ) 41 %', 'd ) 51 %', 'e ) none of these']
Example Output: a

Example Input: Problem: the number 70 can be written as the sum of the squares of 3 different positive integers . what is the sum of these 3 integers ? 
Options: a ) 17 , b ) 16 , c ) 15 , d ) 14 , e ) 13
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