Nutrient rich soil
usually infertile
found in river deltas
found near the base or mountains
contains low levels of potassium

Found in river deltas

Nutrient rich soil is found in the river deltas.

Option B

Explanation:

The river delta contains soil that is deposited in the river bed by various rivers. These rivers flow through a large land surfaces and thereby bring  in enormous amount of nutrient.

Each biotic environment will have a specific type of nutrient that are produced in abundance due to the type of organisms that dwell there, thereby a river delta will contain the silt that is deposited from the various environments through which the river is flowing.

a few examples of ethical concerns involving genetically engineering of humans include

-privacy of genetically tested people

- potential side effects

-long term effects

i think the answer would be d