The correct option is C Terai
Tarai, also spelled Terai, a region of northern India and southern Nepal running parallel to the lower ranges of the Himalayas. A strip of undulating former marshland, it stretches from the Yamuna River in the west to the Brahmaputra River in the east. At its northern edge are numerous springs forming several streams, including the important Ghaghara River, which intersect the Terai (meaning “Moist Land”) and are responsible for its marshy character.