174.Which statement is true regarding transactions? (Choose all that apply.)

174.Which statement is true regarding transactions? (Choose all that apply.)
A.A transaction can consist only of a set of DML and DDL statements.
B.A part or an entire transaction can be undone by using ROLLBACK command .
C.A transaction consists of a set of DML or DCL statements.
D.A part or an entire transaction can be made permanent with a COMMIT.
E.A transaction can consist of only a set of queries or DML or DDL statements.
答案：BC
解析：
A:错误,DDL不涉及事务
B:正确
C:错误，这里是事务包括dml或者dcl语句，dcl是不受事务控制的，因此这里我觉得因该是错误的，但是答案c是正确的
D:错误，commit只能全部事务的提交
E:错误，ddl不涉及事务