The number of districts situated on the bank of Ganga river in Bihar State is :

The correct answer is: C. 12

The districts of Bihar situated on the bank of Ganga river are:

• Araria
• Begusarai
• Bhagalpur
• Buxar
• Darbhanga
• Gaya
• Gopalganj
• Jehanabad
• Katihar
• Lakhisarai
• Munger
• Patna
• Saran
• Samastipur
• Sheikhpura
• Siwan
• Supaul

Option A: 21 is incorrect because there are only 12 districts in Bihar situated on the bank of Ganga river.

Option B: 17 is incorrect because there are only 12 districts in Bihar situated on the bank of Ganga river.

Option D: 6 is incorrect because there are more than 6 districts in Bihar situated on the bank of Ganga river.

Option E: None of the above is incorrect because there are 12 districts in Bihar situated on the bank of Ganga river.