The correct answer is: a) Indo-Gangetic Plain.
The Indo-Gangetic Plain is a vast plain in the northern part of the Indian subcontinent. It is formed by the alluvial deposits of the Indus and Ganges rivers. The plain is home to a large number of people and is one of the most important agricultural regions in the world.
The Deccan Plateau is a large plateau in the southern part of the Indian subcontinent. It is formed by the Deccan Trap, a large volcanic plateau. The plateau is home to a number of different cultures and languages.
The Himalayan Region is a mountain range in the northern part of the Indian subcontinent. It is the highest mountain range in the world and is home to a number of different cultures and languages.
The Coastal Plains are a narrow strip of land along the coast of the Indian subcontinent. They are home to a number of different cultures and languages.
In conclusion, Bihar is predominantly located in the Indo-Gangetic Plain. The Indo-Gangetic Plain is a vast plain in the northern part of the Indian subcontinent. It is formed by the alluvial deposits of the Indus and Ganges rivers. The plain is home to a large number of people and is one of the most important agricultural regions in the world.