Supervision of supervision activities refers to the special legal supervision by the People's Procuratorate on the detention, supervision, release of criminal suspects, the activities of defendants, and the activities of reeducation through labor institutions. According to the definition, which of the following is supervision activities? ["Supervision by the People's Procuratorate on additional prosecutions and arrests by investigating authorities.", 'Observation of the suspect by the detention center at the request of the procuratorate.', 'Supervision by the Procuratorate on the legality of the activities of detaining criminal suspects.', 'Special legal supervision by the procuratorate on whether the administrative proceedings of the court are lawful.']