Which of the following statements regarding the Indian Peninsular Plateau is correct?

a) It is triangular in shape and its relief is highly uneven

b) It is a region with numerous hill ranges like Vindhyas and the Satpuras

c) Aravali hills, one of the oldest ranges of the world, border it on the north-east side

d)It is composed of old crystalline, igneous and metamorphic rocks.