Unless You Accept His 'Final Offer' Your Negotiation Opponent Threatens

Multiple Choice

Unless you accept his 'final offer' your negotiation opponent threatens to scrap the whole deal:

A) His threat is more believable if both parties would be harmed by scrapping the deal
B) His threat is more believable if he has invested resources that lower his return to other options
C) His threat is more believable if he puts his threat 'in writing'
D) His threat is more believable if he has balked at this course of action in the past