Answer: A. The soil in the floodplain is usually fertile
Explanation:
A floodplain can be defined as the flat area which is expected to receive the heavy flow of water due to neighboring water body, which may cause flood. Such floodplains have been proved to be the sites of agriculture since decades due to the rich and fertile soil. As the river or any other water body brings sediments which include essential minerals supporting the growth of the crops. This will solve the problems of daily food needs for the people being settled at the neighboring places.
Earth is composed of four main layers, starting with an inner core at the planet's center, enveloped by the outer core, mantle, and crust. The inner core is a solid sphere made of iron and nickel metals about 759 miles (1,221 kilometers) in radius.
source: nasa
-4x^2-4xy+6y^2 hope this helps
