(B1-MC-12) How many of the following are oxidation-reduction reactions? NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l) Cu (s) + 2AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq) Mg(OH)2 (s) → MgO (s) + H2O (l) N2 (g) + 3H2 (g) → 2NH3 (g) a. 0 b. 1 c. 2 d. 3 e. 4