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 diagonal of a rectangle is 41 cm and its area is 20 sq . cm . the perimeter of the rectangle must be : 
Options: ['a ) 18 cm', 'b ) 28 cm', 'c ) 30 cm', 'd ) 38 cm', 'e ) 42 cm']
Example Output: a

Example 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']
Example Output: b

Example Input: Problem: in the xy - plane , a triangle has vertices ( 0,0 ) , ( 4,0 ) and ( 4,8 ) . if a point ( a , b ) is selected at random from the triangular region , what is the probability that a - b > 0 ? 
Options: a ) 1 / 5 , b ) 1 / 3 , c ) 1 / 2 , d ) 2 / 3 , e ) 4 / 5
Example Output:
c