In which two locations should the Spanning Tree protocol root guard feature be implemented?

Refer to the exhibit.

A. network engineer deployed an older switch with the same spanning-tree priority as the existing root, which caused a network outage.

In which two locations should the Spanning Tree protocol root guard feature be implemented? (Choose two.)

A. on the designated root switch downlinks to the access layer

B. on Layer 3 boundaries in the distribution layer

C. on all the non-root switch facing ports of the access layer

D. globally on all network switches

E. on the access layers root facing ports

Answer: AC