Final answer:
Dave's actions of threatening physical harm to force a business sale constitute duress (option B), which is a form of coercion that can render a contract voidable.
Step-by-step explanation:
When Dave threatens physical harm to force Evan to sell his business for a below-market price, this is an example of duress. Duress occurs when someone is coerced into an action, such as signing a contract, through threats or actual physical harm. This makes the contract voidable at the option of the victim (in this case, Evan). The other options provided, including mistake, fraud, and undue influence, do not apply to the situation described since they refer to different kinds of lawful breaches or influences.
Mistake refers to an erroneous belief about the facts of a contract at the time it is made. Fraud involves intentional deception to secure unfair or unlawful gain. Undue influence is a situation where a person is able to influence another, typically due to a special relationship, but without threats of physical harm.