单选题 A management domain typically contains a large amount of management information. Each individual item of ______ information is an instance of a managed object type. The definition of arelated set of managed ______ types is contained in a Management Information Base(MIB) module. Many such MIB modules are defined. For each managed object type it describes, a MIB______ defines not only the semantics and syntax of that managed object type, but also the method ofidentifying an individual instance so that multiple ______ of the same managed object type can bedistinguished. Typically, there are instances of each managed object ______ within a managementdomain.