Which of the Following Reactions Illustrate the Reaction of a Base

Multiple Choice

Which of the following reactions illustrate the reaction of a base? I.NH₃ + H₂O → NH₄⁺ + OH^-
II) HCl + H₂O → H₃O⁺ + Cl^-
III) NaOH → Na⁺ + OH^-
IV) NH₄⁺ + H₂O → H₃O⁺ + NH₃

A) I only
B) II only
C) I and III
D) I, III, and IV
E) All of the above are reactions of a base.