What will extend a trust boundary (There is a switch interface configuration with separate voice VLAN and data VLAN to, also showing endpoint

What will extend a trust boundary (There is a switch interface configuration with separate voice VLAN and data VLAN to, also showing endpoint
A . Multiple Layers PC
B . IP Phone
C . Access Switch
D . Distribution Switch
E . Core Switch

Answer: B

Explanation:

A Catalyst switch can detect an IP phone via CDP and can instruct the phone to extend a trust boundary to its auxiliary data port. The voice traffic from the phone should be implicitly trusted because the phone is both a Cisco device and a small switch that can be configured and controlled.