Sometimes Liquid Ammonia, NH₃, Is Used as a Solvent Rather

Multiple Choice

Sometimes liquid ammonia, NH₃, is used as a solvent rather than water. Which expression defines the ammonia autoionization counterpart of K_w?

A) [H₃O^][OH^]
B) [NH₃][NH₄^]
C) [NH₂^][NH₄^]
D) [H₃O^][NH₂^]
E) [NH₄^][OH^]