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: if a number is subtracted from its square we get 272 . find the number ? 
Options: ['a ) 7', 'b ) 21', 'c ) 19', 'd ) 15', 'e ) 17']

Ex Output:
e


Ex Input:
Problem: the diameter of a cylindrical tin is 10 cm and height is 5 cm . find the volume of the cylinder ? 
Options: a ) 125 , b ) 155 , c ) 130 , d ) 120 , e ) 100

Ex Output:
a


Ex Input:
Problem: a perfect square is defined as the square of an integer and a perfect cube is defined as the cube of an integer . how many positive integers n are there such that n is less than 1,000 and at the same time n is a perfect square and a perfect cube ? 
Options: a ) 2 , b ) 3 , c ) 4 , d ) 5 , e ) 6

Ex Output:

b