The correct answer is C the extension of the Bill of Rights to the states through selective incorporation
Gitlow v New York in 1925 was a decision by the Supreme Court that stated the state of New York could prohibit advocating violent efforts to overthrow the government. It extended the reach of limitations on federal government authority set forth in the First Amendment.
Mapp v. Ohio in 1961 was a criminal case which the Supreme Court decided that it is forbidden to use unconstitutionally obtained evidence in federal and in states by the incorporation doctrine.
Gideon v. Wainwright in 1963 was a case that the Supreme Court ruled that the states are also required to provide attorneys to defendants in criminal cases who are unable to afford their own attorneys.