Dear Linda
sorry for the misunderstanding, but we didn’t know the context and what kind of people was involved in changing the facilities (young people are now in detention?) You say that they were parents. Ok.
So, I think that the rationale of the right answer (a) may be both the first part of the answer (interest groups) and also the second part – as you say – to explore and recommend alternatives. We may start with groups already interested and committed to, as not only parents (sometimes no committed), but also professionals, prison reform advocates or citizens. Personally, I think that also young people under criminal proceedings may be an interest group to be involved in exploring alternatives, but this is my opinion and perhaps another matter.
Hoping to have been more clear, and more useful
best wishes!