Q: In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Problem: a metallic sheet is of rectangular shape with dimensions 40 m x 30 m . from each of its corners , a square is cut off so as to make an open box . if the length of the square is 8 m , the volume of the box ( in m cube ) is : 
Options: ['a ) 3220 m cube', 'b ) 4140 m cube', 'c ) 2688 m cube', 'd ) 4000 m cube', 'e ) none of these']
A:
c