Final answer:
A delta is formed by constructive erosion when sediment and other materials are carried by a river and deposited at the mouth of the river, forming new land and changing the shape of the coastline.
Step-by-step explanation:
The correct answer is O delta. A delta is formed by constructive erosion. Constructive erosion occurs when sediment and other materials are carried by a river and deposited at the mouth of the river, forming a delta. Deltas are created over a long period of time as the river flows into a body of water, such as a lake or ocean. The deposition of sediment creates new land and changes the shape of the coastline.
Learn more about Constructive Erosion