Refer to the exhibit. An LACP EtherChannel between two directly connected switches is in the configuration process. Which command must be configured on switch SW2s Gi0/1-2 interfaces to establish the

`channel-group 1 mode on` creates a static EtherChannel, which disables LACP negotiation and would prevent an LACP EtherChannel from forming.

`channel-group 1 mode desirable` is a PAgP (Port Aggregation Protocol) mode, not an LACP mode, and would not negotiate an LACP EtherChannel.

For LACP (Link Aggregation Control Protocol) to form an EtherChannel, at least one side must be in 'active' mode to actively initiate the negotiation by sending LACP PDUs. If SW1 is also active or passive, 'active' mode on SW2 will successfully establish the LACP EtherChannel.

`channel-group 1 mode auto` is also a PAgP mode (passively waiting for PAgP PDUs), not an LACP mode. For LACP, the passive mode is `channel-group 1 mode passive`.