Final answer:
Erik, acting in a single agency capacity, owes undivided loyalty to either the buyer or the seller, providing fiduciary duties exclusively to his client and ensuring their interests are primary. Therefore, the correct option is C.
Step-by-step explanation:
When Erik is acting in a single agency capacity in a transaction, it means that he is representing (and owes undivided loyalty) to either the buyer or the seller in a real estate transaction. In this role, Erik must provide fiduciary duties such as confidentiality, obedience, accounting, loyalty, and disclosure exclusively to his client, ensuring that the client's interests are put above all others. This is in contrast to a dual agency situation where the agent represents both parties, which could lead to conflicts of interest.