Given the reaction for the corrosion of aluminum: 4 Al + 3 O2 --> 2 Al2O3, which half-reaction correctly represents the oxidation that occurs?
Al + 3e- --> Al3+
Al --> Al3+ + 3e-
O2 + 4e- --> 2O2-
O2 --> 2O2- + 4e-

Option B, Al --> Al3+ + 3e-

Explanation:

Oxidation is defined as the process of losing electron by a molecule, atom or anion  thereby acquiring oxidation state i.e the positive charge. Reduction on the other hand is the process in which an atom, ion or molecule gains electron and gains negative charge on it.  

For example – In the reaction, H2 + F2 → 2 HF, hydrogen is oxidized H2 → 2 H+ + 2 e-  as it looses electron while fluorine is being reduced F2 + 2 e- → 2 F-

This is happening in the option B

B

Explanation: