In many cases the employee would want her own lawyer present, not the corporation's. This seems to counsel against a right of the corporation to have its lawyer present when the employee is being interviewed. Although I grant that C's wording could be improved. B is out because there is no requirement that sanctions escalate. The other situations involve privileges.
Defense counsel wants corroboration of plaintiff's mental distress.
The D situation certainly raises serious ethical problems for the attorney about whether she can continue to pursue this claim for Plaintiff, but the info is not discoverable by the other side unless plaintiff waives the privilege regarding her conversation with her attorney. D is out because deterrence of others is a legitimate goal of sanctions.