The correct code snippet for detecting a change in OSPF neighbors and displaying an alert message is Option C: This option includes a check for 'OSPF-neighbor-state-change' within the 'Correlation Engine' data returned by the API call. If this key exists and its value is not 0, indicating a state change has occurred, it prints out an alert message "OSPF neighbor change detected!" This logic correctly implements the required functionality.
References := ( Automating Cisco Enterprise Solutions Official Cert Guide )