Answer:
entropy
Explanation:
GPG is an acronym for GNU Privacy Guard, which is considered as free software, is a command-line tool for generating cryptographically secure keys.
These cryptographically secure keys can be created by using entropy, through reliable entropy source, like /dev/random, which in turn derives its entropy from physical devices connected to the machine, such as keyboards, mice, and disks.
Hence, the right answer is ENTROPY
