A.SELECT S.S#,SNAME FROM S WHERE S.S# =(SELECT SC.S# FROM SC WHERE C#='C2') B.SELECT S.S#,SNAME FROM S,SC WHERE S.S#==SC.S# AND C#='C2' C.SELECT S.S#,SNAME FROM S,SC WHERE S.S#=SC.S# AND C#='C2' ORDER BY S.S# D.SELECT S.S#,SNAME FROM S WHERE S.S IN (SELECT SC.S## FROM SC WHERE C#='C2')