The correct option is C Protocol
A protocol is the system of rules and acceptable behaviour used at official ceremonies and occasions. For example, "a breach of Royal protocol". Hence, Option C is correct. Among the rest of the options, formalism means excessive adherence to prescribed forms, statesmanship means skill in managing public affairs, hierarchy means a system in which members of an organization or society are ranked according to relative status or authority.These do not express this meaning, hence incorrect.