Minor travelling to china without parents (who are divorced)

What documents need to be provided to support a visa application for a minor (Under 18) travelling to China without their parents. I understand that we would need to provide their birthcertificate and the passports if the parents under normal circumstances. However, the parents are divorced (but both still have parental rights). Do both parents still need to submit their passports or could one parent submit their passport plus the divorce certificate and an explanation letter?

Similarly, what would the situation be where the parents are divorced and one parent is not contactable? Would a passport and a divorce certificate be acceptable?