Which of the Following Reactions Involves Neither Oxidation nor Reduction

Multiple Choice

Which of the following reactions involves neither oxidation nor reduction?

A) N₂(g) + 3H₂(g) → 2NH₃(g)
B) NH₄NO₂(s) → N₂(g) + 2H₂O(l)
C) Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s)
D) 2CrO₄^2-(aq) + 2H⁺(aq) → Cr₂O₇^2-(aq) + H₂O(l)
E) C₂H₄(g) + H₂(g) → C₂H₆(g)