In which scenario is broker Jamie considered a dual agent while no one else in the firm is?

In the context of agency relationships, Jamie is considered a dual agent when representing both the buyer and the seller within the same transaction. This typically occurs when Jamie is the sole broker involved in facilitating the sale, taking both roles of the seller's and buyer's agent.

In the provided scenario labeled as C, Vivian is acting as the seller's agent and Mark as the buyer's agent. This configuration indicates that both agents represent different clients and are not operating under a dual agency agreement. If Jamie were to represent both the seller and the buyer in the same transaction, then dual agency would apply, as it creates a scenario where the agent has to balance the interests of both parties which could potentially lead to conflicts.

The focus here is on the single-agency representation in the options provided. In essence, Jamie cannot be viewed as a dual agent unless they are representing both the buyer and seller in the same transaction. Thus, the scenario presented in option C highlights the differentiation in agency roles and confirms Jamie's status as a dual agent does not arise in that context.