A landowner embarked on an expedition into a remote jungle, leaving no means to communicate with him. Because property values suddenly began plummeting in the landowner's neighborhood, his son believed that it was imperative to sell his father's property before it became worthless. Having no way to speak to his father ahead of time, the son prepared a deed conveying the property to a buyer, but left the line for the buyer's name blank. He then signed his father's name on it as the grantor, and handed the deed to the buyer. The deed, however, did not include any language regarding the amount the father was to receive in exchange for the property. The buyer believed that the son was the owner of the property. When the father returned, he was happy that the property had been sold.

If the buyer changed his mind and now wishes to have the conveyance set aside, which of the following would be his best argument?
A. The deed was not valid because the rapidly declining property values amounted to extreme duress.
B. The deed was not valid because the buyer was not identified in the writing.
C. The deed was not valid because the consideration for the deed was not contained in the writing.
D. The deed was not valid because the son signed it.