单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2011/9/29/b5d285db52ee4687ad671bc40906669b/13594e3e-0448-4bd5-8f0f-90c79e969f1f.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2011/9/29/b5d285db52ee4687ad671bc40906669b/b53ec2d1-2eff-4b55-8de3-6437ff0a382c.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2011/9/29/b5d285db52ee4687ad671bc40906669b/07270d00-3513-4cf5-a7b8-80f7d990c391.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2011/9/29/b5d285db52ee4687ad671bc40906669b/3c6e1a73-25a9-4281-9fe6-5834d2d70dcd.jpg">