Which of the following expresses an agent's duty of informing clients?

The duty of an agent to inform clients encompasses providing all relevant information that might affect the client's decisions in a real estate transaction. This includes both verified facts and rumors that could potentially influence the outcome. Option B articulates this responsibility by specifying that agents must communicate not just established facts but also hearsay that could have an impact on client choices.

By doing so, agents uphold their fiduciary duty of full disclosure, ensuring that clients are fully informed and can make decisions based on a comprehensive understanding of the situation. This also promotes trust and transparency, which are vital components of the agent-client relationship in real estate.

In contrast, the other options do not fully capture the breadth of this duty. Unknown facts would imply a lack of knowledge on the agent's part, which does not satisfy the obligation to inform. Only favorable facts would compromise the agent's duty of disclosure by withholding important information that clients need for sound decision-making. Client preferences, while essential to understand, do not encompass the range of information the agent must share.