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: two equal triangles constitute rhombus a . if the diagonals of rhombus are 15 cm and 20 cm long . what is the area of each triangle ?
Options: ['a ) 300', 'b ) 150', 'c ) 75', 'd ) 40', 'e ) 20']
Example Output: c

Example Input: Problem: the perimeter of one face of a cube is 20 cm . its volume will be :
Options: a ) 125 cm 3 , b ) 400 cm 3 , c ) 250 cm 3 , d ) 625 cm 3 , e ) none of these
Example Output: a

Example Input: Problem: the diagonals of a rhombus are 15 cm and 12 cm . find its area ?
Options: a ) 70 , b ) 90 , c ) 60 , d ) 80 , e ) 292
Example Output:
b