Final answer:
Oxidation is simply defined as the loss of electrons in a chemical reaction, and when it occurs, the charge of the substance that loses electrons increases.A is the correct answer.
Step-by-step explanation:
A simple definition of oxidation can be understood as the loss of electrons during a chemical reaction.
When a substance undergoes oxidation, it gives up electrons and may also increase its oxidation state due to the loss of these negative charges.
This concept is crucial in understanding redox (reduction-oxidation) reactions, where an oxidizing agent causes another substance to oxidize by taking its electrons, and this is always coupled with a reduction process, which is the gain of electrons.