Hydrogen Sulfide Ion, HS^-, Can React Differently Depending on the Acidity

Multiple Choice

Hydrogen sulfide ion, HS^-, can react differently depending on the acidity of the solution in which it is present.
These two solutions show that the

A) hydrogen sulfide ion is an acid.
B) hydrogen sulfide ion is a base.
C) hydrogen sulfide ion is amphoteric.
D) hydrogen sulfide ion can only react with water.