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 the sum of a number and its square is 240 , what is the number ? 
Options: a ) 15 , b ) 77 , c ) 25 , d ) 87 , e ) 171

Ex Output:
a


Ex Input:
Problem: the area of the largest circle that can be drawn inside a rectangle with sides 18 cm by 14 cm is 
Options: ['a ) 237', 'b ) 154', 'c ) 2376', 'd ) 198', 'e ) 171']

Ex Output:
b


Ex Input:
Problem: the slant height of a cone is 20 cm and radius of the base is 10 cm , find the curved surface of the cone . 
Options: a ) 330 , b ) 159 , c ) 150 , d ) 200 , e ) 628

Ex Output:

e