The correct answer is D.
One should note that a good thesis statement is always the final sentence of the introductory paragraph. It should come as no surprise, then, that this sentence is placed there, as it best demonstrates the position of the author and the task he or she is setting out to do in the rest of the essay.
The rest of the essay, then, will prove the serious drawbacks of ethanol use -- which it does.
Answer:
He shows the reader the consquemces and what will happen if we sont prevent it.
What are the units? I can help you write out an outline if you give me a little more information.