1.請列出下圖二元樹的前序走訪(A)[1, 2, 4, 7, 8, 5, 3, 6, 9, 10] (B)[7, 8, 4, 5, 2, 9, 10, 6, 3, 1] (C)[1, 2, 3, 4, 5, 6, 7, 8, 9, 10] (D)[7, 4, 8, 2, 5, 1, 3, 9, 6, 10]