Step 1: Understanding the Concept:
Drainage basins and riverine fisheries geography of India: the Gandak River is a major north-bank tributary of the Ganga, whereas Dihang, Dhansiri, and Kulsi are tributaries of the Brahmaputra.
Step 2: Detailed Explanation:
River basin geographical drainage in India:
1. Brahmaputra River System Tributaries: Major tributaries include the Dihang (Siang), Dibang, Lohit, Subansiri, Manas, Sankosh, Tista, Dhansiri, Kapili, and Kulsi.
2. Gandak River (B): Originates in the Himalayas of Nepal (as Kali Gandaki) and flows across Bihar to join the Ganga River near Patna (Ganga basin), NOT the Brahmaputra River system.
Step 3: Final Answer:
Therefore, Gandak is NOT a tributary of the Brahmaputra River system, matching option (B).