30. According to the article, which of the following is NOT true? (A) Those who played a traditional Swiss milking song would be sentenced to death for evoking nostalgia in the past. (B) The author considered suicidal attempts as disturbing but inevitable symptoms for those suffering from nostalgia. (C) Ancient research proposed a link between overly lenient education and the development of mental disorders. (D) According to historical documents, soldiers from Switzerland, Russia and the U.S. displayed symptoms of nostalgia.