Microorganisms Are an Essential Part of the Web of Life

Microorganisms are an essential part of the web of life in every environment. Microorganisms in the oceans and in bodies of fresh water capture energy from sunlight and store it in molecules that other organisms use as food. They decompose dead organisms and waste materials from living organisms. And they even make nitrogen available to plants. Jacquelyn C. Black, Microbiology: Principles and Explorations

A) Argument; conclusion: Microorganisms in the oceans ... use as food.
B) Argument; conclusion: And they even make nitrogen available to plants.
C) Argument; conclusion: Microorganisms are an essential part ... environment.
D) Argument; conclusion: They decompose dead organisms ... living organisms.
E) Nonargument.