Explanation/Reference:
A trusted system is one that meets its intended security requirements. It involves sufficiency and effectiveness, not necessarily efficiency, in enforcing a security policy. Put succinctly, trusted systems have (1) policy, (2) mechanism, and (3) assurance.
Source: HARE, Chris, Security Architecture and Models, Area 6 CISSP Open Study Guide, January 2002.

RFC 1661 - The Point-to-Point Protocol (PPP) specifies that the Point-to-
Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams
over point-to-point links. PPP is comprised of three main components:
1 A method for encapsulating multi-protocol datagrams.
2 A Link Control Protocol (LCP) for establishing, configuring, and testing the data-link
connection.
3 A family of Network Control Protocols (NCPs) for establishing and configuring different
network-layer protocols.

Quench

Section: Risk, Response and Recovery
Explanation/Reference:
These people, as employees, are trusted to perform their duties honestly and not take advantage of the trust placed in them.
The following answers are incorrect:
They have had previous contact with law enforcement. Is incorrect because most often it is a person that holds a position of trust and this answer implies they have a criminal background. This type of individual is typically not in a position of trust within an organization.
They conspire with others. Is incorrect because they typically work alone, often as a form of retribution over a percieved injustice done to them.
They deviate from the accepted norms of society. Is incorrect because while the nature of fraudsters deviate from the norm, the fraudsters often hold a position of trust within the organization.

Explanation/Reference:
In a known plaintext attack, the attacker has the plaintext and ciphertext of one or more messages. The goal is to discover the key used to encrypt the messages so that other messages can be deciphered and read.
Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 3rd Ed., chapter 8: Cryptography (page 676). Also check out: Handbook of Applied Cryptography 4th Edition by Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone.