21) Operating systems can best be described as: a. The main control program for a computer device b. A key hardware device that is essential for the computer to function C. A high level computer language such as C++ d. All of the above 22) Digital signatures can best be described as: a. The coupling of DES with RSA to increase security of messages b. A coding system used to transmit data more security C. Electronic authentication, validating the item has not been tampered with d. A type of encryption that enhances the security of messages 23) Digital certificates can best be described as: a. A tool issued by a trusted third party, validating the sender b. A type of encryption that enhances the security of messages C. Electronic authentication, validating the item has not been tampered with d. All of the above 24) A well designed backup and recovery system includes: a. Recovery Module b. Transaction Log C. Database backup d. All of the above 25) A system of recording a user's activity, and system responses is description of: a. Keystroke monitoring b. Trojan Horse C. Malware Viruses d. All of the above 26) The database attributes that individual users have permission to access are defined in the: a. Operating system b. User view c. User manual d. None of the above 27) A table that contains the rules that limit the actions a user can take is: a. System Audit Trails b. System Firewalls C. Deep Packet Inspection d. Database Authorization Table