You have a 4-node ONTAP 9.

This scenario is about iSCSI SAN path visibility after cluster expansion. ONTAP usesSelective LUN Map (SLM)concepts so that hosts do not automatically see every LUN through every node, which would create unnecessary paths. ONTAP documentation explains that with SLM, when a LUN map is created, the LUN is accessible through paths on the node that owns the LUN and its HA partner, and this behavior is controlled through thereporting-nodeslist.

If you wantadditional paths(including non-optimized paths) from newly added nodes, you must ensure the new nodes can be included in the reporting scope for those LUN mappings. ONTAP provides an explicit mechanism for this: the lun mapping add-reporting-nodes command is used before or after data mobility events to add nodes to the reporting-nodes list for a LUN mapping. This directly matches optionC (reporting nodes).

However, even if reporting-nodes is expanded, hosts only gain usable iSCSI access if the target LIFs are reachable/allowed. ONTAP documentation describes thatportsetscan be used with SLM to further restrict access, and when using SLM with portsets, LUNs are accessible on the set of LIFs included in the portset (on the owning node and its HA partner). Therefore, to “allow non-optimized paths from the AFF A250 nodes,” you must verify whether portsets are being used and that the appropriate new iSCSI LIFs are included (or that no restrictive portset blocks them). That makes optionA (port sets)the second correct configuration item.

Option B (switch zoning) applies to FC fabrics, not iSCSI. Option D (failover groups) affects NAS/management LIF failover behavior and does not control SAN LUN reporting visibility in the way SLM/reporting-nodes and portsets do.