Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography. A free implementation of this protocol is available from the Massachusetts Institute of Technology.
Kerberos is available in many commercial products as well. Kerberos was created by MIT as a solution to these network security problems. The Kerberos protocol uses strong cryptography so that a client can prove its identity to a server (and vice versa) across an insecure network connection. After a client and server has used Kerberos to prove their identity, they can also encrypt (confidentiality) all of their communications to assure privacy and data integrity as they go about their business.

The Directive requires that the means be maintained under the sole control of the signatory. This requirement is a particularly difficult one to achieve. One approach is to use different tokens or smart cards for the different transactions involved. The other answers are typical characteristics of digital signatures that can be implemented with public key cryptography.

In digital computers, a bit is in either a one or zero state. In a quantum computer, through linear superposition, a quantum bit can be in both states, essentially simultaneously. Thus, computations consisting
of trail evaluations of binary patterns can take place simultaneously
in exponential time. The probability of obtaining a correct result is
increased through a phenomenon called constructive interference of
light while the probability of obtaining an incorrect result is decreased through destructive interference. Answer a describes optical computing that is effective in applying Fourier and other transformations to data to perform high-speed computations. Light representing large volumes of data passing through properly shaped physical objects can be subjected
to mathematical transformations and recombined to provide the appropriate results. However, this mode of computation is not defined as quantum computing. Answers c and d are diversionary answers that
do not describe quantum computing.

Preventive controls are concerned with avoiding occurrences of risks while deterrent controls are concerned with discouraging violations. Detecting controls identify occurrences and compensating controls are alternative controls, used to compensate weaknesses in other controls. Supervision is an example of compensating control.
Source: TIPTON, Hal, (ISC)2, Introduction to the CISSP Exam presentation.