Which of the following is a true statement about the use of public-key encryption in transmitting messages? a. Public key encryption enables parties to initiate secure communications through an open medium, such as the Internet, in which there might be eavesdroppers.
b. Public key encryption uses a single key that should be kept secure because it is used for both encryption and decryption.
c. Public key encryption only allows the encryption of documents containing text; documents containing audio and video must use a different encryption method.
d. Public key encryption is not considered a secure method of communication because a public key can be intercepted.