River deltas are? 1, caused by the movement of tectonic plates. 2, areas of infertile, rock soil. 3, formed by erosion. 4, created by seafloor spreading.
I think that the answer is 2 because river deltas are formed when sediments are moved somewhere else in order to make the delta. So is there are areas of infertile rock soil it could be easily moved to make a delta
