正解:D
When a legacy device is no longer receiving updates or patches, it is considered to be at the end of life (EOL).
This means the manufacturer has ceased support for the device, and it will no longer receive updates, security patches, or technical assistance. EOL devices pose security risks and are often decommissioned or replaced.
End of support may seem similar but typically refers to the cessation of technical support, whereas EOL means the device is fully retired.
End of business and End of testing do not apply in this context.