The north eastern plateau region of India does not cover which of the following area?

Bihar

The correct answer is Option 4: Bihar

Bihar is mainly a part of the Northern Plains and is not a part of the north-eastern plateau region.

NCERT: The North-Eastern Plateau Region-  This belt covers Chhotanagpur (Jharkhand), Odisha Plateau, West Bengal and parts of Chhattisgarh. It has variety of minerals viz. iron ore coal, manganese, bauxite, mica.