Final answer:
The correct description for the reaction where Aluminum is oxidized is 'a) Aluminum is oxidized because it lost electrons.' This is in accordance with the principle of 'oxidation is loss, reduction is gain' or 'OIL RIG'.
Step-by-step explanation:
The correct statement that describes the reaction where Aluminum (Al) is being oxidized is a) Aluminum is oxidized because it lost electrons. When Al is oxidized to Al³+, it loses three electrons. This process of losing electrons is what we call oxidation, and the electrons can be explicitly written out as products in the half-reaction as Al → Al³+ + 3e⁻. Oxidation-reduction reactions, or redox reactions, are characterized by the transfer of electrons, where the substance losing electrons undergoes oxidation. Thus, in a complete redox reaction, the number of electrons lost by the substance being oxidized must equal the number of electrons gained by the substance being reduced.
Using the mnemonic 'oxidation is loss, reduction is gain' or 'OIL RIG,' it's clear that since aluminum loses electrons in this reaction, it is the substance that is oxidized. Conversely, in the case of oxygen being added to a reaction, it is reduced because it gains electrons, becoming negatively charged as oxide ions (O²⁻).