Final answer:
Chlorine gas (Cl₂) is a common oxidizing agent known for its high electronegativity, which makes it very effective in electron transfer reactions where it gets reduced by oxidizing other substances.
Step-by-step explanation:
Among the options given, Cl₂ (chlorine gas) is a common oxidizing agent. Oxidizing agents are substances that can accept electrons during a chemical reaction and therefore get reduced. Chlorine is a very electronegative element, surpassed only by fluorine, oxygen, and nitrogen, which makes it a potent oxidizing agent.
In its reactions, chlorine often tends to gain electrons and thereby oxidize other substances while it becomes reduced. An example is the reaction of chlorine with phosphorus to produce phosphorus(V) chloride.