Nonrepudiation can BEST be ensured by using:

A.
strong passwords.

B.
a digital hash.

C.
symmetric encryption.

D.
digital signatures.

Explanation:

Digital signatures use a private and public key pair, authenticating both parties. The integrity of the
contents exchanged is controlled through the hashing mechanism that is signed by the private key
of the exchanging party. A digital hash in itself helps in ensuring integrity of the contents, but not
nonrepudiation. Symmetric encryption wouldn’t help in nonrepudiation since the keys are always
shared between parties. Strong passwords only ensure authentication to the system and cannot
be used for nonrepudiation involving two or more parties.