How Was the Defendant in Williams V Bayley Able Successfully

How was the defendant in Williams v Bayley able successfully to establish that the agreement he had entered into with the bank was voidable?

A) The defendant proved that he had not acted as a free and voluntary agent when entering into the agreement..
B) The bank misrepresented the details of the agreement to the defendant.
C) The defendant's son had acted as an agent for the defendant without the latter's knowledge.
D) None of the options provided are correct.