Which two of these IP Phone hardening methods should be applied to these devices?

You are working with Certkiller to develop the methodology to secure IP Phones at their new research facility. Certkiller will be providing IP Phones in their lobby for vendor and guest use. Which two of these IP Phone hardening methods should be applied to these devices? (Choose two.)

A.
Enable GARP.

B.
Disable PC port on phone.

C.
Use signed IP phone firmware.

D.
Disable the Directory button.

E.
Disable the Services button on the IP phone.