What does it mean when a mobile device reaches 'End of Life' (EOL) from its OS vendor, and what security risk does this create?

• A.The handset stops placing calls once the date passes, since the carrier withdraws service for an unsupported model: the security patches continue to arrive over the network
• B.The label affects application compatibility, since developers stop building for the older release: the operating system itself stays secure, with the vendor still issuing fixes
• C.The handset moves onto a reduced maintenance branch automatically, since the vendor keeps a long-term channel for older models: the risk is a slower patch cadence
• D.EOL means the vendor no longer releases security patches for that OS version/device; users continue operating with unpatched vulnerabilities that attackers can exploit indefinitely, as known CVEs accumulate without fixes