What documentation grants express authority to an agent?

The correct answer is the agent's contract with the principal because it explicitly outlines the terms of the relationship between the agent and the principal, detailing the authority granted to the agent to act on behalf of the principal. This contract typically includes specific powers and responsibilities, thus providing a clear framework for the agent's actions and decision-making abilities within the scope defined by the principal.

While options like a letter of agreement or a power of attorney may convey certain permissions or responsibilities, they do not inherently establish the comprehensive authority that a formal contract does. Similarly, an insurance policy is a product of the agent's work and is not a document that grants authority to the agent; rather, it is a contractual agreement between the insurer and the policyholder. The agent's contract is the foundational document that delineates the agent's express authority in their dealings with clients and within the insurance marketplace.