CONFIG_TCP_AO is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

TCP: Authentication Option (RFC5925)

modulename: tcp_ao.ko

configname: CONFIG_TCP_AO

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>TCP: Authentication Option (RFC5925)
In linux kernel since version 4.14.330 (release Date: 2023-11-20)  
TCP-AO specifies the use of stronger Message Authentication Codes (MACs),
protects against replays for long-lived TCP connections, and
provides more details on the association of security with TCP
connections than TCP MD5 (See RFC5925)

If unsure, say N.

source code: