59. Given a binary tree, the result of its 'in-order traversal' is 'BDCAFHEG', and the result of its 'pre-order traversal' is 'ABCDEFHG'. What is the result of its 'post-order traversal'？ (A) DCBHFGEA (B) DCBAEFGH (C) GHFEADCB (D) HFGEDCBA