What can be done to prevent asymmetrical traffic flows from the core should the link between the aggregation switches fail?

Refer to the exhibit.

In this situation, the link between aggregation switches fails. What can be done to prevent asymmetrical traffic flows from the core should the link between the aggregation switches fail?

A.
Implement RHI.

B.
Implement RSTP and MST.

C.
Tune STP costs on access switches.

D.
Advertise the Agg1 switch as the primary route to the core.

Explanation: