单项选择题
A.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/21/c01aecd4a91b4d98be2d28dc9a697bc5/8a9936b0-4038-4a4c-9670-1a1596736157.jpg">
B.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/21/c01aecd4a91b4d98be2d28dc9a697bc5/48d5b6d5-a25e-480f-a79c-7cd5c1a8b9d4.jpg">
C.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/21/c01aecd4a91b4d98be2d28dc9a697bc5/534cb487-1f02-4f4c-bca0-be5e45cd0965.jpg">
D.<br /><img src="https://imgtest.ppkao.com/ExamPaperRes/2013/11/21/c01aecd4a91b4d98be2d28dc9a697bc5/c1c12bdf-35d1-4048-9b73-ee7f3e99db66.jpg">