Refer to the exhibit. An engineer must implement MST using two user- defined instances. Switch101 must always be the root for VLANs 20 and 40. Which two command sets must be applied? (Choose two.)

While setting the priority (`spanning-tree mst 1 priority 4096`) makes Switch101 a strong root candidate, the `root primary` command (option D) is a more explicit and higher-priority method that guarantees the lowest possible priority.

For MST to function correctly and utilize user-defined instances across the network, all switches participating in the MST region must have matching MST configuration, including the region name, revision, and VLAN-to-instance mappings. This ensures they form a single MST region and correctly assign VLANs 20 and 40 to instances 1 and 2, respectively, with `spanning-tree mode mst` enabling the protocol.

Configuring `root secondary` would make Switch101 a backup root, not the primary root, which contradicts the requirement for Switch101 to *always* be the root for the specified VLANs.

To ensure Switch101 is always the root for VLANs 20 and 40 (mapped to MST instances 1 and 2 by the common configuration), the `spanning-tree mst <instance-id> root primary` command must be applied on Switch101 for both instances. This explicitly sets Switch101's bridge priority to a very low value (e.g., 4096), making it the preferred root for those specific instances.

`spanning-tree mode rapid-pvst` configures Rapid Per-VLAN Spanning Tree+, which is a different STP variant and is incompatible with the requirement to implement MST.