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: two identical circles intersect such that their centers and the points at which they intersect form a square of side 4 cm . what is the area of the region where the two circles intersect ? 
Options: ['a ) 16 - 4 pi', 'b ) 4 - pi', 'c ) 2 pi - 4', 'd ) 8 pi - 16', 'e ) pi ^ 2 - 4']

Ex Output:
d


Ex Input:
Problem: what is the smallest positive integer x , such that 1152 x is a perfect cube ? 
Options: a ) 4 , b ) 6 , c ) 8 , d ) 12 , e ) 18

Ex Output:
d


Ex Input:
Problem: if a 1 mm thick paper is folded so that the area is halved at every fold , then what would be the thickness of the pile after 50 folds ? 
Options: ['a ) 100 km', 'b ) 1000 km', 'c ) 1 million km', 'd ) 1 billion km', 'e ) none']

Ex Output:

d