The correct answer is: a) Prevent flooding.
Embankments are constructed along rivers to prevent flooding. They are made of earth, rock, or concrete and are designed to hold back water during floods. Embankments can be used to protect towns and cities, farmland, and other important infrastructure from flooding.
Option b) is incorrect because embankments do not increase irrigation. Irrigation is the process of watering crops artificially. Embankments can be used to control flooding, which can damage crops, but they do not directly increase irrigation.
Option c) is incorrect because embankments do not generate hydropower. Hydropower is electricity that is generated from the flow of water. Embankments can be used to control the flow of water, but they do not directly generate hydropower.
Option d) is incorrect because embankments do not control erosion. Erosion is the process of soil being worn away by wind or water. Embankments can be used to protect soil from erosion, but they do not directly control erosion.