Solution:Conditions which are favourable for the formation of the Deltas are as follows : The river must carry a large amount of sediments. The slope and speed of the river must not be strong enough to remove the sediments deposited by the river.The slope of the sea floor or lake at the river mouth must be gentle or flat. The Large size and volume of the river. Presence of shallow adjoining sea or continental shelf. Thus, A river delta is a landform that forms at the mouth of a river, where the river flows into an ocean, sea, lake, or reservoir.
Deltas form with the deposition of sediments carried by a river. Over long periods, this deposition builds the characteristic geographic pattern of a river delta. Thus option (d) is the most probable answer.
