Which sentence best expresses the central idea of the passage? (the choices are in parenthesis) President Franklin D. Roosevelt was accustomed to seeking relief from hot Washington, D. C. summers and relaxing on weekends aboard the presidential yacht Potomac or at Hyde Park, NY. (In 1942, the U. S. Secret Service were very concerned about the President's continued use of the Potomac.) World War II had brought an attack on Pearl Harbor and had drawn German U-boats close in Atlantic waters. Presidential safety and Presidential health were concerns. (The muggy climate of Washington, D. C. was considered detrimental to his health, affecting his sinuses.) A new retreat, a place to relax, within a 100 mile radius of Washington, D. C. and in the cool mountain air was sought. Several sites were considered, but Camp Hi-Catoctin in the Catoctin Recreational Demonstration Area was selected after the President's first visit on April 22, 1942. (A camp was already built on the site and the estimated conversion cost was $18,650.) It was also almost 10 degrees cooler than in Washington, D. C. (The camp for federal employees' families became the camp of one federal employee, the President of the United States.) Roosevelt quickly renamed the camp "Shangri-La" from James Hilton's 1933 novel, Lost Horizon.