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: 36 people { a 1 , a 2 , . . . , a 36 } meet and shake hands in a circular fashion . in other words , there are totally 36 handshakes involving the pairs , { a 1 , a 2 } , { a 2 , a 3 } , . . . , { a 35 , a 36 } , { a 36 , a 1 } . then size of the smallest set of people such that the rest have shaken hands with at least one person in the set is 
Options: ['a ) 11', 'b ) 12', 'c ) 13', 'd ) 15', 'e ) 18']

Ex Output:
b


Ex Input:
Problem: find the area of the quadrilateral of one of its diagonals is 26 cm and its off sets 9 cm and 6 cm ? 
Options: a ) 188 cm 2 , b ) 150 cm 2 , c ) 168 cm 2 , d ) 195 cm 2 , e ) 987 cm 2

Ex Output:
d


Ex Input:
Problem: the surface area of a sphere is same as the curved surface area of a right circular cylinder whose height and diameter are 14 cm each . the radius of the sphere is 
Options: a ) 3 cm , b ) 4 cm , c ) 6 cm , d ) 7 cm , e ) none

Ex Output:

d