Under what conditions might too much copper go into solution?

Generally, Copper is more soluable in an acidic solution.

In a basic solution, copper ions form hydroxides and carbonates and fall out of solution as insoluable precipitates.

The exception to this rule is hydrogen sulfide.

It is weakly acid, but combines with copper ions to form insoluable copper sulfide.

Another exception is ammonium hydroxide.

This weak base forms a dark blue complex copper ion.

it is b that is the answer.