Implementing Cisco IP Switched Networks (SWITCH v2-0) (#1)

Which two statements are true of loop guard? (Choose two.)

Configure loop guard on root port to help detect and isolate unidirectional link failure.
Configure loop guard when root guard is enabled for optimal loop prevention mechanism.
Configure loop guard on a PortFast-enabled port to ensure optimal loop prevention mechanism.
Configure loop guard on a point-to-point link for an effective loop prevention mechanism.
Configure loop guard to prevent root port from becoming a designated port.