An administrator wishes to enable network port mirroring based on source port. Which feature should be enabled?

vSphere standard switches do not support port mirroring sessions of any kind; port mirroring is only available on vSphere distributed switches.

ERSPAN is a distributed switch feature that encapsulates mirrored frames in GRE headers, allowing traffic from specified source ports to be forwarded to a remote monitoring station across a routed network. It is the only option among the choices that directly implements source-port-based mirroring at the virtual switch level.

NSX Virtual Wire is a network virtualization construct for creating overlay logical networks, not a mechanism for capturing or mirroring port traffic.

VLANs are a Layer 2 segmentation technique for separating broadcast domains and have no role in configuring or enabling port mirroring sessions.