Question

how are deltas formed?
erosion of softer rock
connection of channels
deposition from flow into a lake or an ocean
creation of large, flat areas by flooding deposits

Explanation:

Deltas are formed when a river carrying sediment flows into a lake or ocean. The water slows down, and the sediment is deposited. This process builds up the landform known as a delta. The other options are not the primary mechanism for delta formation. Erosion of softer rock is more related to processes like canyon - cutting. Connection of channels can happen in river systems but is not the key to delta formation. The creation of large, flat areas by flooding deposits is more about floodplains rather than deltas.

Answer:

deposition from flow into a lake or an ocean