552.Which of the following is a valid way of putting a tablespace named DAVE_TBS into hot backup mode?
A.alter tablespace DAVE_TBS backup mode;
B.alter tablespace DAVE_TBS start backup;
C.alter tablespace DAVE_TBS begin backup;
D.alter tablespace DAVE_TBS backup begin;
E.alter tablespace DAVE_TBS backup;
正确答案是C