Which of the following incidents should an approved provider report to the regulatory authority?

When considering which incidents an approved provider must report to the regulatory authority, the scenario of a child missing is paramount. This situation represents a significant safety concern and poses a risk to the child's well-being, thus requiring immediate reporting to ensure the child’s safety and initiate any necessary search or rescue operations. The regulatory authority has protocols in place to handle such incidents, which underscores the seriousness of the situation.

In contrast, while staff disagreements, changes in curriculum, and parental complaints may all be important situations for an organization to manage, they do not reach the level of critical urgency that a missing child situation does. Staff disagreements are typically internal matters, changes in curriculum usually fall under operational decisions, and parental complaints, while valuable feedback, do not pose an imminent safety risk. Therefore, these issues do not necessitate the same level of reporting to regulatory authorities as a missing child does.