Explanation/Reference:
Explanation:
The concept of piggybacking compromises all physical control established. Choice B would be of minimal concern in a disaster recovery environment. Items in choice C are not easily duplicated. Regarding choice D, while technology is constantly changing, card keys have existed for some time and appear to be a viable option for the foreseeable future.

The record-locking option of a database management system (DBMS) serves to eliminate the risk of concurrent updates to a record by different users or transactions. Record locking is a technique of preventing simultaneous access to data in a database, to prevent inconsistent results1. For example, if two bank clerks try to update the same bank account for two different transactions, record locking can ensure that only one clerk can modify the record at a time, while the other has to wait until the lock is released. This way, the record will reflect both transactions correctly and avoid data corruption.
Record locking does not serve to allow database administrators (DBAs) to record the activities of users. This is a function of auditing or logging, which can track the actions performed by users on the database2. Record locking does not affect the ability of DBAs to monitor or audit user activities.
Record locking does not serve to restrict users from changing certain values within records. This is a function of access control or authorization, which can enforce rules or policies on what data users can view or modify2.
Record locking does not affect the permissions or privileges of users on the database.
Record locking does not serve to allow users to lock others out of their files. This is a function of encryption or password protection, which can secure files from unauthorized access or modification3. Record locking does not affect the security or confidentiality of files on the database.
References:
* Record locking - Wikipedia1
* Database security - Wikipedia2
* File system permissions - Wikipedia3