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: find the area of the quadrilateral of one of its diagonals is 30 cm and its off sets 10 cm and 6 cm ? 
Options: a ) 189 cm 2 , b ) 150 cm 2 , c ) 240 cm 2 , d ) 177 cm 2 , e ) 187 cm 2

Ex Output:
c


Ex Input:
Problem: what is the smallest positive integer x such that 864 x is the cube of a positive integer 
Options: a ) 6 , b ) 12 , c ) 9 , d ) 5 , e ) 2

Ex Output:
e


Ex Input:
Problem: two circular frames are kept one above the other . frame x has a diameter of 16 cm and frame y has a diameter of 12 cm . what fraction of the surface of frame x is not covered by frame y ? 
Options: ['a ) 3 / 5', 'b ) 7 / 16', 'c ) 12 / 16', 'd ) 24 / 12', 'e ) 2 / 3']

Ex Output:

b