Consider the reaction that occurs when copper is added to nitric acid.
[tex]\[Cu (s) + 4 HNO_3(aq) \longrightarrow Cu(NO_3)_2(aq) + 2 NO_2(g) + 2 H_2O (l)\][/tex]
What is the reducing agent in this reaction?
A. [tex]\(Cu\)[/tex]
B. [tex]\(NO_3^{-}\)[/tex]
C. [tex]\(Cu(NO_3)_2\)[/tex]
D. [tex]\(NO_2\)[/tex]