Under What Circumstances Might the "Soft Opt-In" Rule Apply in Relation

Under what circumstances might the "soft opt-in" rule apply in relation to direct marketing?

A) When an individual has not consented to the marketing.
B) When an individual's details are obtained from their inquiries about buying a product.
C) Where an individual's details have been obtained from a bought-in marketing list.
D) Where an individual is given the ability to unsubscribe from marketing emails sent to him.