1.B
2. http://fun.jjang0u.com/chalkadak/view?db=160&no=407657#vw_dut_set
http://fun.jjang0u.com/chalkadak/view?db=160&no=407345#vw_dut_set
http://fun.jjang0u.com/articles/view?db=105&no=235483#vw_dut_set
3.중복확인했음