The correct answer is Ganga List of rivers in Bihar:
Bagmati
Budhi gandak: It runs parallel to Gandak.
Gandak: It originates in Tibet. Gandak joins Ganga in sonepur.
Ganga: Ganga has the highest catchment area in the state. Mahatma Gandhi Setu which is built on this river connects Patna and hajipur . It entersat chausa. Ghaghara, gandak, Bagmati, Kosi, and kali-Kosi is its northern tributary. Son, karmanasa, and punpun is its southern tributary.
Ghaghra: It is also known as Saryu. It originates in Nepal.
Kamla: Kamla barrage has been constructed on this river.
Phalgu
Kosi: Kosi is known as the sorrow of Bihar.
Mahananda: It originates in Sikkim. Mahananda joins Ganga at Nawabganj in Bangladesh.