Final answer:
The correct answer is 4) ACCTM. All other options are valid Access file extensions.
Step-by-step explanation:
The correct answer is 4) ACCTM.
All of the given options are related to Microsoft Access, which is a popular database management system. The file extensions used in Access databases include ACCDB, ACCDE, and ACCDT.
However, ACCTM is not a valid file extension in Microsoft Access. It may be a typographical error or a made-up extension.