The error message shows that the datafile C:\ORANT\DATABASE\STUDENT.ORA is damaged. You know this file belongs to the STUDENT tablespace, which was read-only, and you have a backup of the tablespace. However, you remember that you had one of your junior DBAs change the tablespace to read-write a couple of days ago and it is not included in your routine backup strategy. As a result, you have to use the backup when the tablespace STUDENT was read-only to perform the recovery. In order to make the database available, you must take the damaged tablespace STUDENT offline. Type
ALTER DATABASE DATAFILE 'C:\ORANT\DATABASE\STUDENT.ORA' OFFLINE;
at the prompt and press Enter.