To ensure that sensitive data, such as Personally Identifiable Information (PII), is not modified, the bank should implement file integrity monitoring (FIM). FIM tracks changes to files and provides alerts if unauthorized modifications are detected, ensuring data integrity. Full disk encryption protects data at rest but does not prevent or monitor modifications. Network access control (NAC) manages access to the network but doesn't monitor file changes. User behavior analytics (UBA) detects suspicious user activities but is not focused on file integrity.