Final answer:
Pretty Good Privacy (PGP) is the encryption system that can verify e-mail authenticity and encrypt data in transmission, using a combination of public and private keys.
Step-by-step explanation:
Pretty Good Privacy (PGP) is a public key encryption system that can verify the authenticity of an e-mail sender and encrypt e-mail data in transmission. It allows users to send and receive messages securely by providing both encryption, which protects the contents of the messages, and digital signature, which verifies the identity of the sender. PGP uses a system of private and public keys to achieve this: a public key is used to encrypt the message, and a private key is used to decrypt it.