14. 美國國務卿給國會的某年年度報告中，有一份關於福爾摩莎的文件，其部份內容如下：「At the request of Tauketok, the ruler of the eighteen tribes south of Liangkiau, and between the range of hills east of it and the Eastern Sea including the bay known as the Southern Bay of Formosa where the crew of the American bark Rover were murdered by the Koaluts, I, Charles W. Le Gendre, United States consul for Amoy and Formosa give this as a memorandum of the understanding arrived at between myself and the said Tauketok in 1867, the same having been approved by the United States Government and assented to, I believe by the foreign ministers at Pekin viz： Cast-aways will be kindly treated by any of the eighteen tribes under Tauketok. If possible, they are to display a red flag before landing.」從內容來看，這份文件，對後來的哪一個歷史事件的發生提供了重要的理論基礎？ (A)羅妹號事件 (B)牡丹社事件 (C)中法戰爭 (D)臺灣民主國成立。