正解:A
The script that should be applied to receive an SNMP trap and a critical-level log message when a user switches to configuration mode is the one that uses the EEM (Embedded Event Manager) applet with specific commands for SNMP trap generation and logging. The correct script would contain the event cli command to specify the CLI event, action commands for sending an SNMP trap (snmp-trap) and for logging a message (syslog) at a critical level.