Which of the following is false regarding duress?

a. It can result from threats of a violent act.
b. Regardless of the form or content of the threat, if a coerced party is able to prove that he is unusually timid or that he was in an unusually vulnerable state of mind when he acqulesced to the other party's threats, he may invoke the duress defense even if an ordinarily reasonable person would not have been Intimidated by such threats.
c. It can result from economic threats
d. It is one of the few areas of law that is based on the objective bellef of the parties.