[单选]  设有Teachers表，该表的定义如下：   CREATETABLETeachers(    TnoCHAR(8)PRIMARYKEY,     TnameVARCHAR(10)NOTNULL,     AgeTINYINTCHECK(AgeBETWEEN25AND65))插入语句中，不能正确执行的是（ ）。

a. INSERT INTO Teachers VALUES('T100','张宏',NULL) b. INSERT INTO Teachers(Tno,Tname,Age) VALUES('T100','张宏',30) c. INSERT INTO Teachers(Tno,Tname) VALUES('T100','张宏') d. INSERT INTO Teachers VALUES('T100','张宏')