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: 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 3 cm . find the whole surface of the cylinder ? 
Options: ['a ) 520 sq cm', 'b ) 840 sq cm', 'c ) 440 sq cm', 'd ) 120 sq cm', 'e ) 5 sq cm']

Ex Output:
c


Ex Input:
Problem: in measuring the sides of a rectangle , one side is taken 20 % in excess and the other 10 % in deficit . find the error per cent in area calculated from the measurement ? 
Options: ['a ) 12 % deficit', 'b ) 10 % excess', 'c ) 8 % excess', 'd ) 9 % excess', 'e ) none of these']

Ex Output:

c