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

Option (b) is correct because the left-bank tributaries join the Ganga in the sequence of Gomati (near Varanasi), Ghaghara (near Chhapra), Gandak (near Patna), and Kosi (near Katihar) as one moves from West to East. Option (a) is the most tempting error but is incorrect because the Gomati’s confluence lies further west (upstream) than that of the Ghaghara. The core concept tested is the spatial distribution and drainage pattern of the major Himalayan tributaries within the Ganga river system.