In the Following Reaction, Which Species Is the Reducing Agent $\rightarrow$

In the following reaction, which species is the reducing agent? 3Cu + 6H⁺ + 2HNO₃ $\rightarrow$ 3Cu²⁺ + 2NO + 4 H₂O

A) H⁺
B) Cu
C) N in NO
D) Cu²⁺
E) N in HNO₃