Explanation/Reference:
The Bell-LaPadula model is a confidentiality model for information security based on the military classification of data, on people with clearances and data with a classification or sensitivity model. The Biba, Clark-Wilson and Brewer-Nash models are concerned with integrity.
Source: HARE, Chris, Security Architecture and Models, Area 6 CISSP Open Study Guide, January 2002.

TCP provides a full-duplex, connection-oriented, reliable, virtual circuit. It
handles the sequencing and retransmission of lost packets.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3:
Telecommunications and Network Security (page 85).

Explanation/Reference:
Users can obtain certificates with various levels of assurance. Here is a list that describe each of them:
- Class 1/Level 1 for individuals, intended for email, no proof of identity For example, level 1 certificates verify electronic mail addresses. This is done through the use of a personal information number that a user would supply when asked to register. This level of certificate may also provide a name as well as an electronic mail address; however, it may or may not be a genuine name (i.e., it could be an alias). This proves that a human being will reply back if you send an email to that name or email address.
- Class 2/Level 2 is for organizations and companies for which proof of identity is required Level 2 certificates verify a user's name, address, social security number, and other information against a credit bureau database.
- Class 3/Level 3 is for servers and software signing, for which independent verification and checking of identity and authority is done by the issuing certificate authority
Level 3 certificates are available to companies. This level of certificate provides photo identification to accompany the other items of information provided by a level 2 certificate.
- Class 4 for online business transactions between companies
- Class 5 for private organizations or governmental security
References:
http://en.wikipedia.org/wiki/Digital_certificate veriSign introduced the concept of classes of digital certificates:
Also see:
Source: TIPTON, Harold F. & KRAUSE, Micki, Information Security Management Handbook, 4th edition (volume 1), 2000, CRC Press, Chapter 3, Secured Connections to External Networks (page 54).

Explanation/Reference:
The Data/Information Owner is ultimately responsible for the protection of the data. It is the Data/ Information Owner that decides upon the classifications of that data they are responsible for.
The data owner decides upon the classification of the data he is responsible for and alters that classification if the business need arises.
The following answers are incorrect:
Security Administrator. Is incorrect because this individual is responsible for ensuring that the access right granted are correct and support the polices and directives that the Data/Information Owner defines.
User. Is Incorrect because the user uses/access the data according to how the Data/Information Owner defined their access.
Auditor. Is incorrect because the Auditor is responsible for ensuring that the access levels are appropriate.
The Auditor would verify that the Owner classified the data properly.
References:
CISSP All In One Third Edition, Shon Harris, Page 121

Explanation/Reference:
Security administrator functions include user-oriented activities such as setting user clearances, setting initial password, setting other security characteristics for new users or changing security profiles for existing users. Data owners have the ultimate responsibility for protecting data, thus determining proper user access rights to data.
Source: TIPTON, Hal, (ISC)2, Introduction to the CISSP Exam presentation.