A circular disc is to be made by using iron and aluminium, so that it acquires maximum moment of inertia about its geometrical axis. It is possible with
A. aluminimum is at the interior and iron surrounds it
B. iron is at the interior and aluminimum surrrounds it
C. aluminium and iron layers are in alternate order
D. sheet of iron is used at both external surfaces and aluminium sheet as inner material
