In a public key infrastructure (PKI), which of the following may be relied upon to prove that an online transaction
was authorized by a specific customer?

A.
Nonrepudiation

B.
Encryption

C.
Authentication

D.
Integrity

Explanation:
Nonrepudiation, achieved through the use of digital signatures, prevents the claimed sender from later denying
that they generated and sent the message. Encryption may protect the data transmitted over the Internet, but
may not prove that the transactions were made. Authentication is necessary to establish the identification of all
parties to a communication. Integrity ensures that transactions are accurate but does not provide the
identification of the customer.