单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/12/7054af7c5e8140af97125969491d5d5d/a7c086b7-fd02-414b-b39c-30dacc1b845b.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/12/7054af7c5e8140af97125969491d5d5d/728c38bd-14d0-4d06-81c4-77f926e8ffad.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/12/7054af7c5e8140af97125969491d5d5d/4648f1e1-3fed-4456-9210-27d0df704679.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/12/7054af7c5e8140af97125969491d5d5d/144d96fe-524d-480d-aa6f-5217cff92b63.jpg">