处理金融交易时，以下哪个操作序列能保证资金转账的原子性？（账

BEGIN; UPDATE accounts SET balance=balance-100 WHERE id='A'; COMMIT; UPDATE accounts SET balance=balance+100 WHERE id='B';

BEGIN; SAVEPOINT s1; UPDATE... ROLLBACK TO s1;

BEGIN; UPDATE accounts SET balance=balance-100 WHERE id='A'; UPDATE accounts SET balance=balance+100 WHERE id='B'; COMMIT;

SET autocommit=0; UPDATE... WHERE id='A'; UPDATE... WHERE id='B';