Final answer:
The Chief Information Security Officer (CISO) should be most concerned with data remnants when bringing the CRM service in-house due to the possibility of sensitive data being left behind on third-party cloud services.
Step-by-step explanation:
The Chief Information Security Officer (CISO) should be most concerned with data remnants when bringing the CRM service in-house. Data remnants refer to traces of data that remain on a system even after it has been deleted or removed. Since both companies outsource CRM services to competing and incompatible third-party cloud services, there is a possibility that sensitive data could be left behind on those systems. It is crucial for the CISO to ensure that all data remnants are properly identified, secured, and disposed of to minimize the risk of data breaches and unauthorized access.