正解:B
RSPAN consists of at least one RSPAN source session, an RSPAN VLAN, and at least one RSPAN destination session. You separately configure RSPAN source sessions and RSPAN destination sessions on different network devices. To configure an RSPAN source session on a device, you associate a set of source ports or source VLANs with an RSPAN VLAN.
Traffic monitoring in a SPAN session has these restrictions: + Sources can be ports or VLANs, but you cannot mix source ports and source VLANs in the same session.
Reference:
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-
2_55_se/configuration/guide/3750xscg/swspan.html
Therefore in this question, we cannot configure a source VLAN because we configured source ports for RSPAN session 1 already.