单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/454c839d367e41d98193db01170dcd01/96901540-ad9e-41f3-9f6f-f4c04bd326f6.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/454c839d367e41d98193db01170dcd01/c572841c-808c-4237-bf7b-a3a2b1342964.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/454c839d367e41d98193db01170dcd01/6c51639b-6d53-4e27-a517-1000965e5d02.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2014/8/27/454c839d367e41d98193db01170dcd01/78b81cbe-675f-4d9b-8873-cecf2847c5c6.jpg">