To solve this question, the user needs to know about the ROWID data type in databases.
The ROWID is a pseudo column added by Oracle to all tables, which stores the row's unique identifier. The ROWID is represented in hexadecimal format, and it uniquely identifies each row in a table.
Now, let's go through each option and explain why it is right or wrong:
A. Binary data upto 4GB: This option is incorrect because ROWID is not a data type that stores binary data.
B. Character data upto 4 GB: This option is incorrect because ROWID is not a data type that stores character data.
C. A hexadecimal string representing the unique address of a row in its table: This option is correct. The ROWID data type stores a hexadecimal string that represents the unique address of a row in its table.
D. Binary data stored in an external file: This option is incorrect because ROWID is not a data type that stores binary data in an external file.
The Answer is: C