You execute the following command in your Certkiller .com production database to change the width of the CUST_NAME column of the CUSTOMERS table： ALTER TABLE customers MODIFY （cust_nameVARCHAR2 （40）） / When you execute the command， it displays the following error message： ERROR at line 1： ORA-00054： resource busy and acquire with NOWAIT specified What could be the reason for the error message？（）
- AThe database instance is not available.
- BThe ALTER TABLE command does not have WAIT option
- CThe table or a row in the table is currently locked by another user session.
- DThe database instance is busy processing other user sessions commands.
- EThe CUSTOMERS table has no long running query active at the time when this request is made.
- FThe server process executing the ALTER TABLE command is busy with another command executio