Why does the possibility of floods increase in the plains of Himalayan rivers?

Correct answer: Due to low slope and large water volume

Direct answer: Option C is correct. Himalayan rivers carry abundant water because they receive rainfall and, in many cases, meltwater from snow and glaciers. When these rivers enter the plains, the land slope becomes gentle. A gentler slope reduces velocity, so the river cannot move all its water and sediment efficiently. If heavy rain or rapid snowmelt adds more water, the channel may overflow its banks and cause floods. Option C gives the two important linked conditions: low slope and large water volume. Option A is not the main general cause; sea waves do not normally create floods far across the river plains. Option B is wrong because a completely dry river cannot produce this kind of flooding. Option D is wrong because Himalayan rivers are connected with glaciers and snow, not their total absence. Remember the chain: much water plus gentle slope plus limited channel capacity can produce flooding.