Which of the following incidents will require reporting to OPC?

Under PIPEDA, any breach of security safeguards involving personal information that poses a real risk of significant harm (RROSH) requires reporting to the Office of the Privacy Commissioner of Canada (OPC). In the scenarios given, sending a sales report with aggregated information (option A) or a file with client data to wrong processors who cannot identify the clients (option B), or blocking an attempted hack (option C), may not necessarily pose a RROSH. However, a nursing home releasing an email with everyone's email address in the "to" section unredacted during a freedom of information request (option D) potentially exposes individuals to a risk of spam, phishing, and other malicious activities, thereby posing a real risk of significant harm. This constitutes a breach requiring reporting to the OPC.