An administrator notices that a sensor's local AV signatures are out-of-date.

VMware Carbon Black Cloud Endpoint Standard uses a hybrid approach to determine the reputation of files on the endpoints. It combines local scan, which uses signature-based detection to identify known malware, and cloud scan, which uses cloud-based analytics and machine learning to identify unknown or emerging threats. When a sensor’s local AV signatures are out-of-date, it means that the local scan cannot detect the latest malware variants that have been added to the signature database. However, this does not affect the cloud scan, which can still determine the reputation of newly discovered files based on their behavior, characteristics, and context. Therefore, the effect of having out-of-date local AV signatures is that the reputation is determined by cloud reputation, which is more accurate and up-to-date than signature-based detection. The other options are not correct, because the sensor does not prompt the end user, automatically block, or fail to block a new file based on the local AV signatures alone. References: Carbon Black Cloud Endpoint Standard - Technical Overview, View and Update Signature Versions, Endpoint Standard: How to verify AV Signatures are updating