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: the length of a rectangle is halved while its width is also halved . what is the % change in area ?
Options: a ) 25 % , b ) 30 % , c ) 50 % , d ) 65 % , e ) 75 %

Ex Output:
e

Ex Input:
Problem: a and b are two circles . the radius of a is four times as large as the diameter of b . what is the ratio between the areas of the circles ?
Options: ['a ) 1 : 8 .', 'b ) 1 : 2 .', 'c ) 1 : 24 .', 'd ) 1 : 64 .', 'e ) 1 : 6 .']

Ex Output:
d

Ex Input:
Problem: the radius of a cylindrical vessel is 7 cm and height is 4 cm . find the whole surface of the cylinder ?
Options: a ) 484 , b ) 771 , c ) 440 , d ) 767 , e ) 1981

Ex Output:
a