In Pure Liquid Ammonia, the Equilibrium Concentrations of Both NH₄⁺

In pure liquid ammonia, the equilibrium concentrations of both NH₄⁺ and NH₂^- are 3 × 10^-14 M. Which of the following equations always holds for liquid ammonia solutions?

A) pNH₄⁺ = log [pNH₄⁺]
B) pNH₄⁺ = 27.0
C) pNH₄⁺ - pNH₂^- = 13.5
D) pNH₄⁺ = 27.0 - pNH₂^-
E) pNH₄⁺ + pNH₂^- = 13.5