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

Example Input: Problem: the radius of a cylinder is 2 r units and height is 3 r units . find the curved surface ? 
Options: a ) 18 π r 2 , b ) 12 π r 2 , c ) 3 π r 2 , d ) 6 π r 2 , e ) 9 π r 2
Example Output: b

Example Input: Problem: a semicircle has a radius of 9 . what is the approximate perimeter of the semicircle ? 
Options: a ) 16 , b ) 25 , c ) 33 , d ) 46 , e ) 58
Example Output: d

Example Input: Problem: find the area of the quadrilateral of one of its diagonals is 50 cm and its off sets 15 cm and 5 cm ? 
Options: a ) 100 cm 2 , b ) 150 cm 2 , c ) 200 cm 2 , d ) 250 cm 2 , e ) 500 cm 2
Example Output:
e