<u>Answer:</u> The oxidizing agent in the given reaction is copper.
<u>Explanation:</u>
Oxidation reaction is the reaction in which an atom looses its electrons. Here, oxidation state of the atom increases.

Reducing agents are the agents that reduces the other substance and itself gets oxidized. They undergoes reduction reactions.
Reduction reaction is the reaction in which an atom gains electrons. Here, the oxidation state of the atom decreases.

Oxidizing agents are the agents that oxidizes the other substance and itself gets reduced. These agents undergoes reduction reactions.
For the given chemical reaction:

The half reactions for the above reaction are:
Oxidation half reaction: 
Reduction half reaction: 
From the above reactions, copper is gaining electrons and thus is getting reduced and is considered as an oxidizing agent.
Carbon is loosing its electrons. Thus, it is getting oxidized and is considered as a reducing agent.
Hence, the oxidizing agent in the given reaction is copper.