下列对于教学视频中“学生选课”数据库的基本表定义中，正确的是（ ）
A、CREATE TABLE S( SNO CHAR(6), SN CHAR(10) NOT NULL, SEX CHAR(2) DEFAULT '男', SB DATE, SD CHAR(16), CHECK (SEX IN ('男','女')), PRIMARY KEY (SNO));
B、CREATE TABLE C( CNO CHAR(6) PRIMARY KEY, CN CHAR(10) NOT NULL, PC CHAR(10), FOREIGN KEY (PC) REFERENCES C(CNO));
C、CREATE TABLE C( CNO CHAR(6), CN CHAR(10) NOT NULL, PC CHAR(6) FOREIGN KEY, PRIMARY KEY (CNO));
D、CREATE TABLE SC( SNO CHAR(6) PRIMARY KEY, CNO CHAR(6) PRIMARY KEY, GRADE DEC(4,1), FOREIGN KEY (SNO) REFERENCES S(SNO), FOREIGN KEY (CNO) REFERENCES C(CNO), CHECK (GRADE BETWEEN 0 AND 100));