Refer to the exhibit. If IEEE 802.1w is in use for this network design, what are two locations where spanning-tree root can be placed to ensure the least-disruptive Layer 2 failover for clients within

Placing the root at Switch A, a core or remote switch, means that any failure requires reconvergence across more of the topology, increasing disruption time for VLAN 3 and 4 clients.

Switch B is not directly adjacent to the segments hosting VLANs 3 and 4, so root placement there increases the spanning-tree diameter and the number of switches affected during a failover event.

Switch C and Switch D are the distribution-layer switches directly aggregating the access layer where VLANs 3 and 4 reside. Placing the RSTP root at either distribution switch ensures that a root failure triggers a local, rapid failover to the other distribution switch without requiring reconvergence across the entire topology. RSTP's rapid port-role transitions allow the alternate root to take over in milliseconds, minimizing client disruption.

Switch D, as the secondary distribution switch, provides a redundant root placement option. If Switch C is root and fails, Switch D immediately assumes root responsibility with minimal disruption because RSTP has already pre-negotiated port roles and states between the two distribution switches.