Metals are extracted from their ores by a wide variety of techniques. The most common ores are oxides. Most metals are obtained by direct treatment of theirs ores with chemical agents, but the extraction of certain others require electrolysis. An example of the former type of process is the extraction of iron from its oxide, described by the following equation :
`Fe_(2) O_(3) + 3C rarr 2Fe + 3CO`
The relative ease of extraction of a metal from its oxide can be estimated using the Ellingham diagram, as shown in the figure.
The diagram plots the free energies of formation of various oxides per mole of consumed oxygen as a function of absolute temperature.

Which of the following best explains why the free energy of formation of `Fe_(2)O_(3)` becomes less negative as the temperature is increased.

Options

A. The free energy of formation is independent of the absolute temperature.
B. Entropy drops as a result of the consumption of oxygen.
C. At low temperature, the free energy of formation becomes less dependent on the enthalpy of formation.
D. As entropy increases, the free energy of formation increases.

Answer

B