Discuss whether either of the following contracts will be unenforceable on the ground that voluntary consent is lacking:
(a) Simmons finds a stone in his pasture that he believes to be quartz. Jenson, who also believes that the stone is quartz, contracts to purchase it for $10. Just before delivery, the stone is discovered to be a diamond worth $1,000.
(b) Jacoby’s barn is burned to the ground. He accuses Goldman’s son of arson and threatens to have the prosecutor bring a criminal action unless Goldman agrees to pay him $5,000.Goldman agrees to pay.