In this case, according to the given information, it turns out convenient for us to realize that the concept acid and base we should use here is based off the Bronsted-Lowry one, which says that an acid is a hydrogen donor. In such a way, since water accepts one H ion as it goes to H3O⁺, we infer it is C. Base and the H2S the acid.
Also, we can tell HS⁻ is the conjugate base and H3O⁺ the conjugate acid.
In metallic bonding, electrons exists as "sea of electrons" which means similar to how waves are free to go anywhere in ocean, these electrons are free to roam around the crystal of the metal.