In a corrosion cell, which of the following is NOT required:

In a corrosion cell, the essential components for corrosion to occur include an anode, a cathode, and an electrolyte. The anode is where oxidation occurs, leading to the loss of electrons, while the cathode is where reduction takes place, resulting in electron gain. The electrolyte provides the medium through which ions can move, completing the electrical circuit between the anode and cathode.

Oxygen, while it can accelerate the corrosion process as an oxidizing agent, is not a mandatory component for a corrosion cell to exist. Corrosion can occur in environments that are devoid of oxygen, as long as there is an anode, a cathode, and some form of electrolyte to allow for electrochemical reactions. For example, in anaerobic conditions, microorganisms can contribute to corrosion even without the presence of oxygen. Thus, the requirement of oxygen is not absolute for a corrosion cell, making it the correct response in this context.