Which of the following best describes the agreement involving a mandatary?

The correct choice highlights that the agreement involving a mandatary is characterized by a formalized service agreement with clearly defined duties. In the context of agency law, a mandatary is someone who is given authorization to perform acts on behalf of another party (the mandator). This relationship is formalized through a contract, which outlines specific responsibilities, obligations, and the scope of authority the mandatary has.

This contractual nature ensures that both parties are aware of their roles and the expectations associated with the agreement, which helps to prevent misunderstandings or disputes. The formalized aspect typically includes details such as the tasks to be performed, compensation, and any relevant timelines, making it distinctly different from less formal arrangements.

The other options, while they present alternative types of agreements, do not capture the essential characteristics of a mandatary agreement. A non-binding understanding lacks the enforceability and specific duties typically found in a mandatary arrangement. A handshake agreement suggests a much more informal setup with vague responsibilities, while an informal arrangement based solely on trust does not establish the necessary clarity and legal standing that a formalized service agreement would provide.