【单选题】

设有关系R(A，B，C)和S(C，D)与关系代数表达式( ) 　　π_A，B，D(σ_R.C=S.C(R×S)) 等价的SQL语句是
A．SELECT*FROM R，S WHERE C=C

B．SELECT A，B，D FROM R，S WHERE C=C
C．SELECT A，B，D FROM R，S WHERE R=S
D．SELECT A，B FROM R WHERE(SELECT D FROM S WHERE C=