单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/a8cf530250cc424abea379b958467e58/07679be7-0491-4a9d-a0ae-0bad3a665d87.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/a8cf530250cc424abea379b958467e58/a04ee98d-9e30-4f85-853d-83500c918f51.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/a8cf530250cc424abea379b958467e58/375d828d-6f3d-4261-a47b-c6c079197ab1.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/a8cf530250cc424abea379b958467e58/dfbe9607-8be0-4618-aaba-baa0e9baee80.jpg">