In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: two spherical balls lie on the ground touching . if one of the balls has a radius of 10 cm , and the point of contact is 12 cm above the ground , what is the radius of the other ball ( in centimeters ) ? 
Options: a ) 14 , b ) 15 , c ) 16 , d ) 18 , e ) 20
Example Output: b

Example Input: Problem: if 12 men and 16 boys can do a piece of work in 7 days and 13 men together will 24 boys can do it in 4 days . compare the daily work done by a man with that of a boy . 
Options: a ) 1 : 4 , b ) 1 : 2 , c ) 1 : 3 , d ) 2 : 1 , e ) 4 : 1
Example Output: b

Example Input: Problem: what is the maximum number of points that 10 circles of different radii intersect ? 
Options: a ) 24 , b ) 26 , c ) 33 , d ) 90 , e ) 100
Example Output:
d