With reference to the Himalayan rivers Joining the Ganga downstream of Prayagraj from West to East,which one of the following sequences is correct ?

1. A

   Ghaghara - Gomati - Gandak - Kosi

   Ghaghara–Gomati–Gandak–Kosi. Gomati meets the Ganga west of Ghaghara’s confluence.

2. B

   Gomati - Ghaghara - Gandak - Kosi

   Gomati–Ghaghara–Gandak–Kosi. West-to-east after Prayagraj.

3. C

   Ghaghara - Gomati - Kosi – Gandak

   Ghaghara–Gomati–Kosi–Gandak. Order of Gomati/Ghaghara and Gandak/Kosi both wrong.

4. D

   Gomati - Ghaghara - Kosi - Gandak

   Gomati–Ghaghara–Kosi–Gandak. Gandak joins west of the Kosi.

Summary. Official key is (b). Downstream of Prayagraj, from west to east, the left-bank sequence is Gomati, then Ghaghara, then Gandak, then Kosi (each joining the Ganga further east). Ghaghara is east of Gomati; Kosi is east of Gandak.