Introduction:
In Bihar, there are several rivers that flow through the state. However, when it comes to north flowing rivers in Bihar, none of the options provided in the question are correct. Let's discuss each option and understand why they are not north flowing rivers.

Explanation:
1. Bagmati River: The Bagmati River is a major river in Bihar, but it does not flow northwards. It originates in Nepal and flows southwards, passing through several districts in Bihar, including Sitamarhi, Muzaffarpur, and Patna, before eventually joining the Ganges River.

2. Kamla River: The Kamla River is also a significant river in Bihar, but it does not flow northwards either. It originates in Nepal and flows southwards, forming a natural boundary between Bihar and Nepal. It passes through districts like Madhubani, Darbhanga, and Samastipur before joining the Bagmati River.

3. Kosi River: The Kosi River is one of the major rivers in Bihar, but it does not flow northwards. It originates in Tibet and flows southwards through Nepal before entering Bihar. In Bihar, it meanders through several districts, including Saharsa, Madhepura, and Khagaria, before eventually joining the Ganges River.

4. Gandak River: The Gandak River is another significant river in Bihar, but it does not flow northwards as well. It originates in Nepal and flows in an easterly direction before entering Bihar. It passes through districts like West Champaran, East Champaran, and Saran before joining the Ganges River.

Conclusion:
None of the rivers mentioned in the options provided (Bagmati, Kamla, Kosi, Gandak) flow northwards in Bihar. Therefore, the correct answer is "None of the above/More than one of the above."