In PKI, a key pair consists of: (Select TWO).

A.
A key ring

B.
A public key

C.
A private key

D.
Key escrow

E.
A passphrase

Explanation:
In a PKI the sender encrypts the data using the receiver’s public key. The receiver decrypts the data using his own private key. The key pair consists of these two
keys.
Incorrect Answers:

A: There is no concept of key ring within a Public-Key Infrastructure.
D: A key escrow is not included in a PKI key pair.
Key escrow) is an arrangement in which the keys needed to decrypt encrypted data are held in escrow so that, under certain circumstances, an authorized third
party may gain access to those keys.
E: A PKI key pair contains two keys, and does not include a passhrase. A passphrase is a sequence of words or other text used to control access to a computer
system, program or data. Passphrases are particularly applicable to systems that use the passphrase as an encryption key.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, Sixth Edition, Sybex, Indianapolis, 2014, pp 140, 262, 279-285
http://en.wikipedia.org/wiki/Keyring_%28cryptography%29