which feature will configuring a SOHO network in which all ports on the public untrusted network will be forwarded to one workstation connected to the LAN?

Demilitarized zone (DMZ).

Explanation:

Demilitarized zone is a kind of security assurance scheme used by network administrator to detect network breach even before it gets to the secured network.

The private LAN is protected with a firewall and a DMZ is configured to allow access by untrusted users, on another workstation, which is a duplicate of the companies private local address.