Final answer:
A real estate broker should primarily offer advice and opinions to their principal, either a seller or buyer, due to their fiduciary relationship.
Step-by-step explanation:
A real estate broker should provide advice and opinions primarily to the principal, who is the client they have a fiduciary relationship with. The principal is either the seller or the buyer, depending on who has engaged the services of the broker. Advice or opinions for parties other than the principal should be given with caution and typically only general information should be provided unless they have some agreement or representation that allows otherwise.