Backward-chaining mode - the expert system backtracks to determine if a given
hypothesis is valid. Backward-chaining is generally used when there are a large number of
possible solutions relative to the number of inputs.
Incorrect answers are:
In a forward-chaining mode, the expert system acquires information and comes to a conclusion
based on that information. Forward-chaining is the reasoning approach that can be used when
there is a small number of solutions relative to the number of inputs.
Blackboard is an expert system-reasoning methodology in which a solution is generated by the
use of a virtual blackboard, wherein information or potential solutions are placed on the blackboard
by a plurality of individuals or expert knowledge sources. As more information is placed on the
blackboard in an iterative process, a solution is generated.
Lateral-chaining mode - No such expert system mode.
Sources:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of
Computer Security, John Wiley & Sons, 2001, Chapter 7: Applications and Systems Development
(page 259).
KRUTZ, Ronald & VINES, Russel, The CISSP Prep Guide: Gold Edition, Wiley Publishing Inc.,
2003, Chapter 7: Expert Systems (page 354).

The principle that the development team has taken into consideration when using data from an old production database in a secure testing environment is that biometric data must be protected from disclosure. Biometric data is a type of data that is derived from the physical or behavioral characteristics of a person, such as fingerprints, iris patterns, or voice recognition. Biometric data is used for identification or authentication purposes, and it is considered as sensitive or personal data that should be protected from unauthorized or malicious access, modification, or disclosure. The development team has taken this principle into consideration when they used data from an old production database in a secure testing environment, as they ensured that the biometric data was not exposed or compromised during the testing phase of the application.
Biometric data cannot be changed, separate biometric data streams require increased security, or the biometric devices are unknown are not the principles that the development team has taken into consideration when using data from an old production database in a secure testing environment. Biometric data can be changed, as it may vary due to aging, injury, or disease, and it may need to be updated or replaced. Separate biometric data streams do not necessarily require increased security, as it depends on the type, quality, and purpose of the biometric data. The biometric devices are not unknown, as the development team should be aware of the specifications, capabilities, and limitations of the biometric devices that they are using for the application.
References: Official (ISC)2 Guide to the CISSP CBK, Fifth Edition, Chapter 5: Identity and Access Management, page 407.

BGP (Border Gateway Protocol) is a routing protocol that is used to exchange route information between public autonomous systems (AS). An AS is a network or a group of networks that are under the same administrative control and share a common routing policy. BGP is the standard protocol for interconnecting different AS on the Internet, allowing them to exchange information about the reachability and availability of IP prefixes. BGP is also used for traffic engineering, load balancing, and policy-based routing. The other options are not routing protocols that are used to exchange route information between public autonomous systems, as they either operate within a single AS, use a different addressing scheme, or are obsolete.
References: CISSP - Certified Information Systems Security Professional, Domain 4. Communication and Network Security, 4.1 Implement secure design principles in network architectures, 4.1.1 Apply secure design principles to network architecture, 4.1.1.1 OSI and TCP/IP models; CISSP Exam Outline, Domain 4.
Communication and Network Security, 4.1 Implement secure design principles in network architectures, 4.1.1 Apply secure design principles to network architecture, 4.1.1.1 OSI and TCP/IP models