Answer: The correct option is (A).
Step-by-step explanation:
Oxidation Is a reaction in which loss of an electrons from an atom is involved in a reaction is known as oxidation.
Reduction Is a reaction in which gain of an electrons by an atom is involved in a reaction is known as reduction.
In a chemical reaction, an iron atom became the ion
which means that iron atom by loosing two electrons from its valence shell has oxidized into positively charged ion.

So, the correct option (.A)