设有关系R(A，B，C)和S(C，D)与关系代数表达式：πA，B，D(σR.C=S.C(R×S)) 等价的SQL语句是（ ）。

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