Exam CIPM topic 1 question 110 discussion

SCENARIO -
Please use the following to answer the next question:
You lead the privacy office for a company that handles information from individuals living in several countries throughout Europe and the Americas. You begin that morning’s privacy review when a contracts officer sends you a message asking for a phone call. The message lacks clarity and detail, but you presume that data was lost.
When you contact the contracts officer, he tells you that he received a letter in the mail from a vendor stating that the vendor improperly shared information about your customers. He called the vendor and confirmed that your company recently surveyed exactly 2000 individuals about their most recent healthcare experience and sent those surveys to the vendor to transcribe it into a database, but the vendor forgot to encrypt the database as promised in the contract. As a result, the vendor has lost control of the data.
The vendor is extremely apologetic and offers to take responsibility for sending out the notifications. They tell you they set aside 2000 stamped postcards because that should reduce the time it takes to get the notice in the mail. One side is limited to their logo, but the other side is blank and they will accept whatever you want to write. You put their offer on hold and begin to develop the text around the space constraints. You are content to let the vendor’s logo be associated with the notification.
The notification explains that your company recently hired a vendor to store information about their most recent experience at St. Sebastian Hospital’s Clinic for Infectious Diseases. The vendor did not encrypt the information and no longer has control of it. All 2000 affected individuals are invited to sign-up for email notifications about their information. They simply need to go to your company’s website and watch a quick advertisement, then provide their name, email address, and month and year of birth.
You email the incident-response council for their buy-in before 9 a.m. If anything goes wrong in this situation, you want to diffuse the blame across your colleagues. Over the next eight hours, everyone emails their comments back and forth. The consultant who leads the incident-response team notes that it is his first day with the company, but he has been in other industries for 45 years and will do his best. One of the three lawyers on the council causes the conversation to veer off course, but it eventually gets back on track. At the end of the day, they vote to proceed with the notification you wrote and use the vendor’s postcards.
Shortly after the vendor mails the postcards, you learn the data was on a server that was stolen, and make the decision to have your company offer credit monitoring services. A quick internet search finds a credit monitoring company with a convincing name: Credit Under Lock and Key (CRUDLOK). Your sales rep has never handled a contract for 2000 people, but develops a proposal in about a day which says CRUDLOK will:
Send an enrollment invitation to everyone the day after the contract is signed.
Enroll someone with just their first name and the last-4 of their national identifier.
Monitor each enrollee’s credit for two years from the date of enrollment.
Send a monthly email with their credit rating and offers for credit-related services at market rates.
Charge your company 20% of the cost of any credit restoration.
You execute the contract and the enrollment invitations are emailed to the 2000 individuals. Three days later you sit down and document all that went well and all that could have gone better. You put it in a file to reference the next time an incident occurs.
Regarding the notification, which of the following would be the greatest concern?