Is it unethical for a seller to bid on their own property?

It is considered acceptable for a seller to bid on their own property if they announce their intention to do so prior to the auction. This practice is known as "reserve bidding" or "protective bidding," and it is pivotal for maintaining transparency in the auction process. By making the announcement, the seller ensures that all participants are aware of their presence in the bidding, which mitigates any feelings of deception or unfair advantage that could arise if the seller were to bid without announcement. This ethical guideline encourages a fair and open bidding environment, allowing all participants to make informed decisions as they engage in the auction.

The other choices present scenarios that do not account for the importance of prior announcement, which is key to maintaining ethical standards during the auction.