Explanation:

A full backup is a comprehensive copy of all data on a system, including every program, data file, and system configuration file. This type of backup is complete, ensuring all information can be recovered, though it can be time-consuming and requires significant storage. Restoration (a) is the process of recovering data, not a backup type. Bootstrap (b) refers to the initial OS loading. A differential backup (c) only backs up data changed since the last full backup, not *every* file. Therefore, 'full' is the correct term for a backup containing a copy of every program, data, and system file on a computer.