Some prokaryotes can use inorganic (carbonless) compounds as an energy source or growth. eukaryotes must use a compound containing carbon for energy. which of the following is an example of a prokaryotic organism gaining energy from an inorganic compound?
a. antibiotics prevent bacteria from growing.
b. iron bacteria cause iron in water wells to rust.
c green algae undergo photosynthesis to grow.

B. Iron bacteria cause iron in water wells to rust.

Explanation:

Inorganic compounds are all substances formed by atoms or molecules of at least two different elements, and which do not contain in their structure carbon atoms forming chains and bound to hydrogen. In some situations carbon may appear in the structure of the compound, but due to the way it is bonded, it is considered inorganic, as is the case with CO2 and Na2CO3.

Some protists feed on inorganic compounds, as stated in the question above. They derive from the inorganic compounds the energy needed for your body to function. An example of this is the iron bacteria that cause rust in water wells.

The correct sentence is - Classification organizes organisms based on their characteristics.

Classification is an important aspect for organism classification because it allows scientists to identify organisms, group them and properly name them  based on the similarities found in these organisms genetics, evolution etc.