Why do scanning tools may report a root Trojan Horse compromise when it is run against an lOScomponent?

A.
IOS is based on BSD UNIX and is thus subject to a Root Trojan Horse compromise.

B.
The scanning software is detecting the hard-coded backdoor password in IOS.

C.
Some IOS versions are crashable with the telnet option vulnerability.

D.
The port scanning package mis-parses the IOS error messages.