Mark Hires Joe's Real Estate Agency to Sell His Property

Mark hires Joe's real estate agency to sell his property, telling Joe he has lost too much money playing the stock market to afford to keep it up. Then Mark wins the three million-dollar lottery! Joe reads this in the newspaper and that afternoon makes a contract with Sharon to sell the property. Is the contract valid?

A) No, the agency terminated because of the change in conditions.
B) No, the agent has no right to sell without consent.
C) Yes, Mark would have to notify Joe if he wanted to stop the sale.
D) Yes, Joe had apparent authority to sell.