A metallic sheet is of rectangular shape with dimensions 100 m x 50 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 10 m, the volume of the box (in m cube) is: Select:  A) 42500 m cube  B) 20000 m cube  C) 44140 m cube  D) 24000 m cube  E) none of these

Rationale: "explanation : l = ( 100 - 20 ) m = 80 m , [ because 10 + 10 = 20 ] b = ( 50 - 20 ) m = 30 m , h = 10 m . volume of the box = ( 80 x 30 x 8 ) m cube = 24000 m cube . option d"
Answer: D