In her persuasive speech, Martha spoke about the alleged espionage by the Chinese, and the possible theft of U.S. nuclear armament secrets. She got the audience to think about the possibility that China could one day rise up and use high-tech nuclear weapons against the United States. She challenged them to monitor Senate hearings on the problem and to get involved by writing or e-mailing their congress persons. What form of motivation did Martha successfully employ in her speech?