B. In metal casting process, solidification time is a function of the volume of a casting and its surface area as expressed by Chrovinov's rule [TTS =Cm(V/A)2 ]. This equation can also be used in designing the shape of the riser in casting mould. In a sand casting process, the calculated total solidification time of the cast part is 2 minutes. Generally, the riser's total solidification time is at least 25% longer than the total solidification time of the cast part. Given there are TWO (2) options for the riser shape: i. Cylindrical, with diameter of 60mm and height of 60mm, and ii. Cuboid, with sides of 60mm60mm60mm. The mold constant is 2s/mm2 and exponent is 2 . Determine which shape (cuboid or cyclinder) is suitable for the riser. State your reason. (6 MARKS)