A company uses PGP to ensure that sensitive email is protected. Which of the following types of
cryptography is being used here for the key exchange?

A.
Symmetric

B.
Session-based

C.
Hashing

D.
Asymmetric

Explanation:
PGP combines symmetric-key encryption and public-key encryption. The message is encrypted using a
symmetric encryption algorithm, which requires a symmetric key. Each symmetric key is used only once
and is also called a session key.
Incorrect Answers:
B: They key is a session key, but it is calculated using symmetric encryption.
C: PGP using hashing to create a digital signature from the plaintext, not for the key exchange.
D: PGP uses symmetric-key encryption, not asymmetric.

http://en.wikipedia.org/wiki/Pretty_Good_Privacy
Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 272-273