Which of the following actions could signify an agent operating under implied authority?

The action that signifies an agent operating under implied authority is notifying a buyer about new listings. Implied authority refers to the agent's ability to perform acts that are reasonably necessary to execute their duties, even if not explicitly stated. In a real estate context, it is reasonable for an agent to inform a potential buyer about new listings as part of their role in assisting with the buying process. This action can be seen as a normal and expected duty of an agent, aimed at fulfilling the principal's goal of selling a property.

In contrast, actions such as setting the price of a property or executing contracts without consent may exceed the boundaries of what is typically permitted under implied authority. Advertising on behalf of the principal, while a common task, usually requires explicit authority to ensure alignment with the principal's marketing strategies. Thus, notifying a buyer aligns with the implied duties of an agent, reflecting an understanding of their role in facilitating communication and providing information related to the needs of the buyer.