Merkle-Hellman Knapsack is a Public Key Algorithm Pg 206 Krutz: CISSP Prep Guide: Gold Edition.
Not A:
"DES describes the Data Encryption Algorithm (DEA) and is the name of the Federal Information Processing Standard (FIPS) 46-1 that was adopted in 1977..." pg 195 Krutz: CISSP Prep Guide: Gold Edition.
Not B:
"The best-known symmetric key system is probably the Data Encryption Standard (DES)." pg 195 Krutz: CISSP Prep Guide: Gold Edition.
Not C:
"The German military used a polyalphabetic substitution cipher machine called the Enigma as its principal encipherment system during World War II." Pg 185 Krutz: CISSP Prep Guide: Gold Edition.

Explanation/Reference:
Risk reduction should be applied equally to the initiation phase, the development phase, and to the disposal phase.
Within the initiation phase a preliminary risk assessment should be carried out to develop an initial description of the confidentiality, integrity, and availability requirements of the system.
The development phase include formal risk assessment which identifies vulnerabilities and threats in the proposed system and the potential risk levels as they pertain to confidentiality, integrity, and availability.
This builds upon the initial risk assessment carried out in the previous phase (the initiation phase). The results of this assessment help the team build the system's security plan.
Disposal activities need to ensure that an orderly termination of the system takes place and that all necessary data are preserved. The storage medium of the system may need to be degaussed, put through a zeroization process, or physically destroyed.
Incorrect Answers:
A: Risk reduction should be applied to all phases equally, not mostly to the initiation phase.
B: Risk reduction should be applied to all phases equally, not mostly to the development phase.
C: Risk reduction should be applied to all phases equally, not mostly to the disposal phase.
References:
Conrad, Eric, Seth Misenar and Joshua Feldman, CISSP Study Guide, 2nd Edition, Syngress, Waltham,
2012, pp. 1091-1093

Explanation/Reference:
Explanation:
The concealment cipher is a symmetric key, transposition cipher where the words or characters of the plaintext message are embedded in a page of words or characters at a consistent interval.
Incorrect Answers:
A: Transposition cyphers moves the original values around.
C: The substitution cipher substitutes bits, characters, or blocks of characters with different bits, characters, or blocks.
D: Steganography is a technique used to hide data in another media type so that the presence of the data is masked.
Reference:
Miller, David R, Microsoft CISSP Training Kit, O'Reilly Media, 2013, California, p. 156 Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, pp. 774, 777

This is very obvious, the operators are responsible of making operative tasks that deals with the hardware and software implementations, they can handle the hardware and put t in condition for the user, be in charge of the backup and restore procedures and
Mounting the disk or tapes for the backup. Those are all common tasks. When we talk about the data entry, is the user who has to make does, If the operator do that too, what is the user going to do?

Reference: pg 5 Tittel: CISSP Study Guide