【单选题】
View the Exhibit and examine the parameters.<br /> <img src="https://nimg.ppkao.com/2018-08/chenfang/2018080115355081586.jpg?sign=aa435942cde0c797320cad067119242d&t=62d271a0" /><br /> User A executes the following command to update the TRANS table： SQL> UPDATE B.trans SET tr_amt=tr_amt+500 WHERE c_code=’C005’； <br /> Before user A issues a COMMIT or ROLLBACK command， user B executes the following command onthe TRANS table： <br /> SQL> ALTER TABLE trans MODIFY （tr_type VARCHAR2（3））； <br /> What would happen in this scenario（）
A、The ALTER TABLE command modifies the column successfully.
B、The DDL operation gets higher priority and transaction for user a is rolled back.
C、The ALTER TABLE command waits indefinitely until user a ends the transaction.
D、The ALTER TABLE command fails after waiting for 60 seconds due to the resource being busy.
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