Network architect is recommending that a customer move from a three-tier campus LAN topology to a two-tier topology that routes traffic distribution layer provides firewall services and STP root guard. As a best practice, where should firewall services and STP root guard be important topology? 

These security features should be implemented at both the network access layer and the core. 

These security features should be implemented at the core. 

These security features should be implemented at the network access layer. 

Firewall services features should be implemented at the core, and STP root guard be implemented at the access layer