Refer to the exhibit. What is a feature of this spanning-tree topology?

A.
VLANs are not restricted to access-switch pairs.

B.
Only one aggregation-to-access uplink is active at a given time.

C.
If the link between access-switch pairs is broken, the return IP path may be broken.

D.
Uplink failures on access layer switches will not break connectivity between servers and service modules in the aggregation layer.