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: if the side length of square b is sqrt ( 3 ) times that of square a , the area of square b is how many times the area of square a ? 
Options: ['a ) 9', 'b ) 6', 'c ) 4', 'd ) 3', 'e ) 2']
Example Output: d

Example Input: Problem: the radius of a cylindrical vessel is 7 cm and height is 2 cm . find the whole surface of the cylinder ? 
Options: a ) 281 , b ) 396 , c ) 440 , d ) 767 , e ) 1981
Example Output: b

Example Input: Problem: a certain rectangular crate measures 20 feet by 20 feet by 20 feet . a cylindrical gas tank is to be made for shipment in the crate and will stand upright when the crate is placed on one of its six faces . what should the radius of the tank be if it is to be of the largest possible volume ? 
Options: a ) 4 , b ) 5 , c ) 6 , d ) 8 , e ) 10
Example Output:
e