The most important function of diplomacy, regardless of its scope or its actors, is communication. In a sense diplomacy is communication itself. Another major function of diplomacy is representation. The main instrument of representation is embassies and its main actors are ambassadors, consulates, attaches and other diplomatic personnel. Monitoring the receiving state is one of the oldest functions of diplomacy. The aim of monitoring is to gather information about the receiving state and report this information to the sending state. The correct answer is Choice C.