Which of the following is NOT a contractual duty of the principal to the agent?

The correct identification of the duty that is NOT a contractual obligation of the principal to the agent is the duty to obstruct. In an agency relationship, the principal has several fundamental duties to the agent, including the duty to reimburse the agent for expenses incurred on behalf of the principal, the duty to indemnify the agent for losses suffered while acting within the scope of their authority, and the duty to cooperate with the agent in the performance of their duties. These duties facilitate the agent's ability to execute their responsibilities effectively and uphold the agency relationship.

The notion of a duty to obstruct, on the other hand, does not align with the fundamental principles of agency law. Such a duty would inherently hinder the agent's ability to perform their tasks and would be contrary to the principal's obligations to support and enable the agent's actions in pursuing the principal's interests. Therefore, the duty to obstruct does not exist within the framework of the principal-agent relationship and is correctly identified as not being a contractual duty of the principal.