KB included in the reference also confirms C is the correct answer. Here is another KB also confirming; https://docs.netapp.com/ontap-9/index.jsp?topic=%2Fcom.netapp.doc.pow-dap%2FGUID-AE2302D3-E489-43FE-B64F-1D351DAC6787.html

Explanation
You can use ONTAP System Manager or the command line interface to disable the unused Ethernet ports in an ONTAP 9.8 cluster. ONTAP System Manager is a web-based graphical user interface that enables you to manage storage systems, clusters, and resources. The command line interface is a text-based interface that enables you to perform administrative tasks using commands. Both methods allow you to modify the network port settings and remove the ports from the broadcast domain. Active IQ Config Advisor and Active IQ Unified Manager are not methods to disable the unused Ethernet ports, but tools to monitor and optimize the cluster performance and configuration. References :- Monitor the reachability of network ports in ONTAP 9.8 and later, Map network ports using ONTAP 9.8 or later, Map network ports using ONTAP 9.7 or earlier