A real estate agent representing the buyer tells the seller that the buyer would be willing to pay much more than the asking price. Which duty did the agent owe the principal in this situation?

The answer is: Confidentiality

Explanation:

A Real State Buyer Agent has to comply with a series of fiduciary duties known as COLD AC:

Care Obedience Loyalty Disclosure Accounting Confidentiality

Do to confidentiality responsibility, they cannot either:

disclose the seller's willingness to take a price lower than the list price, nor disclose the buyer's willingness to pay a price higher than the offer price.