Final answer:
Fuels classified as inorganic lack both carbon and hydrogen simultaneously. Illustrations of inorganic compounds include water and carbon dioxide. Option D, denoting inorganic, stands as the accurate solution.
Step-by-step explanation:
In the field of chemistry, the categorization of substances into organic and inorganic compounds relies heavily on the presence of carbon. Notably, fuels classified as inorganic are characterized by their absence of carbon. Although inorganic compounds may contain hydrogen, as seen in instances such as water (H₂O) and the hydrochloric acid (HCl) produced by the stomach, they lack the simultaneous occurrence of carbon and hydrogen seen in organic compounds. Classic organic compounds used as fuels, like propane, butane, and methane (hydrocarbons), are exclusively comprised of carbon and hydrogen.
A distinctive feature surfaces when comparing organic and inorganic compounds: the absence of both carbon and hydrogen in the latter. Carbon dioxide (CO₂), often acknowledged as inorganic, serves as an example, containing carbon while lacking hydrogen. Thus, when confronted with the task of classifying a substance as organic or inorganic, the decisive factor becomes the absence of carbon-hydrogen pairs, unmistakably indicating an inorganic classification. Therefore, in consideration of this, the correct answer is option D, confirming the inorganic nature of substances lacking the characteristic combination of carbon and hydrogen.