Definition: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Input: Question: Approximately how many NSA personnel are stationed at Fort Meade? Passage:Initially called Camp Annapolis Junction, the post was opened as "Camp Admiral" in 1917 on acquired for a training camp. The post was called Camp Meade Cantonment by 1918, Camp Franklin Signal Corps school was located there and in 1919, the Camp Benning tank school—formed from the World War I Camp Colt and Tobyhanna schools—was transferred to the fort before the Tank Corps was disbanded. Renamed to Fort Leonard Wood (February 1928 – March 5, 1929), the fort's Experimental Motorized Forces in the summer and fall of 1928 tested vehicles and tactics in expedition convoys (Camp Meade observers had joined the in-progress 1919 Motor Transport Corps convoy). In 1929, the fort's 1st Tank Regiment encamped on the Gettysburg Battlefield. During World War II, Fort Meade was used as a recruit training post and prisoner of war camp, in addition to a holding center for approximately 384 Japanese, German, and Italian immigrant residents of the U.S. arrested as potential fifth columnists. The Second U.S. Army Headquarters transferred to the post on June 15, 1947; and in 1957, the post became headquarters of the National Security Agency.
 Links: a. Fort Leonard Wood b. Second United States Army c. Tank Corps of the American Expeditionary Forces d. National Security Agency
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
d