Final answer:
The most ethically dubious situation would be when a lawyer represents an artist in negotiation with a company that they have an ownership interest in, as this presents a conflict of interest.
Step-by-step explanation:
The most ethically dubious situation would be option d.) Lawyer represents artist in negotiation with company that they have an ownership interest in. This scenario presents a conflict of interest where the lawyer's personal stake in the company could compromise their ability to provide unbiased and objective legal advice to the artist. The lawyer's duty to act in the best interest of the client is undermined by their financial interest in the outcome of the negotiation.