Disproportionation is a process in which a substance can act only as a reducing agent. can act only as an oxidizing agent. is both an oxidizing and a reducing agent. is neither an oxidizing nor a reducing agent.

Disproportionation is a process in which a substance acts as
C) both an oxidizing and a reducing agent.

In disproportionation, a compound breaks down into two compounds, with one acting as an oxidizing agent and one as a reducing agent. It is important to note that it is not the original compound acting as both, but two distinct product compounds.