单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/13/b45aa929b60940dcb4069dd1e64ab8a6/6cf239f9-6176-4f2e-90ee-768cdc20f805.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/13/b45aa929b60940dcb4069dd1e64ab8a6/50f59be1-8d1d-4055-9a17-3cd67ec219e7.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/13/b45aa929b60940dcb4069dd1e64ab8a6/752704e0-c886-4291-bc81-9d7c9d24b716.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/13/b45aa929b60940dcb4069dd1e64ab8a6/17dd12e9-d491-4e11-b01b-67fb06323297.jpg">