When dead plants decompose and nitrogen is returned to the soil, the interaction is between which two spheres?
a. biosphere and atmosphere
b. geosphere and atmosphere
c. atmosphere and geosphere
d. biosphere and geosphere

When nitrogen is return to the soil from decomposing plant matter, the interaction is between the D. biosphere and the geosphere.

The biosphere comprises all living things in the planet. Plants are living things and when they die and get decomposed, the nitrogen in them leaves the biosphere because the plants are dead.

The nitrogen goes to the geosphere which comprises of:

Because the nitrogen goes to the soil which is made up of rocks, we can conclude that it goes to the geosphere which means that the interaction described in the question is definitely between the geosphere and biosphere.

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D. biosphere and geosphere

Explanation:

Biosphere is the sum of all the ecosystem. The biosphere house all the living things . The biosphere is composed of recycling of matter and the abundant of various factors like sunlight and oxygen that can keep life . Water is another major factor that contribute to life existence. Other elements like phosphorus , nitrogen, oxygen and hydrogen contributes to the building block of life in the form of carbohydrate, fats , protein and lipids.

The geosphere compose of the lithosphere, hydrosphere and the atmosphere and this is strictly the lifeless earth.

The interaction whereby dead plant(biosphere) decompose to add nitrogen to the soil (Geosphere) is an interaction between biosphere and geosphere.