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: when magnified 1,000 times by an electron microscope , the image of a certain circular piece of tissue has a diameter of 2 centimeter . the actual diameter of the tissue , in centimeters , is 
Options: ['a ) 0.005', 'b ) 0.002', 'c ) 0.001', 'd ) 0.0005', 'e ) 0.0002']

Ex Output:
b


Ex Input:
Problem: a hall is 15 meters long and 15 meters wide . if the sum of the areas of the floor and the ceiling is equal to the sum of the areas of four walls , what is the volume of the hall ( in cubic meters ) ? 
Options: a ) 975.5 , b ) 1250.5 , c ) 1465.5 , d ) 1687.5 , e ) 1824.5

Ex Output:
d


Ex Input:
Problem: how much greater is the combined area in square inches of the front and back of a rectangular sheet of paper measuring 11 inches by 11 inches than that of a rectangular sheet of paper measuring 5.5 inches by 11 inches ? 
Options: a ) 50 % , b ) 87 % , c ) 100 % , d ) 187 % , e ) 200 %

Ex Output:

c