Attenuation is the loss of signal strength as it travels. The longer a cable, the more at tenuation occurs, which causes the signal carrying the data to deteriorate. This is why standards include suggested cable-run lengths. If a networking cable is too long, attenuation may occur. Basically, the data are in the form of electrons, and these electrons have to "swim" through a copper wire. However, this is more like swimming upstream, because there is a lot of resistance on the electrons working in this media. After a certain distance, the electrons start to slow down and their encoding format loses form. If the form gets too degraded, the receiving system cannot interpret them any longer. If a network administrator needs to run a cable longer than its recommended segment length, she needs to insert a repeater or some type of device that will amplify the signal and ensure it gets to its destination in the right encoding format. Attenuation can also be caused by cable breaks and malfunctions. This is why cables should be tested. If a cable is suspected of attenuation problems, cable testers can inject signals into the cable and read the results at the end of the cable.
The following answers are incorrect:
Crosstalk - Crosstalk is one example of noise where unwanted electrical coupling between adjacent lines causes the signal in one wire to be picked up by the signal in an adjacent wire.
Noise - Noise is also a signal degradation but it refers to a large amount of electrical fluctuation that can interfere with the interpretation of the signal by the receiver.
Delay distortion - Delay distortion can result in a misinterpretation of a signal that results from transmitting a digital signal with varying frequency components. The various components arrive at the receiver with varying delays.
Following reference(s) were/was used to create this question:
CISA review manual 2014 Page number 265 Official ISC2 guide to CISSP CBK 3rd Edition Page number 229 & CISSP All-In-One Exam guide 6th Edition Page Number 561

This step is not a part of RISK ANALYSIS.
A risk analysis has three main goals: identify risks, quantify the impact of potential threats,
and provide an economic balance between the impact of the risk and the cost of the
associated countermeasure. Choosing the best countermeasure is not part of the risk
analysis.
Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-
Hill/Osborne, 2002, chapter 3: Security Management Practices (page 73).
HARRIS, Shon, Mike Meyers' CISSP(R) Certification Passport, 2002, McGraw-Hill, page
12.

Explanation/Reference:
Digital Signal level 1 (DS-1) is the framing specification used for transmitting digital signals at 1.544 Mbps on a T1 facility. DS-0 is the framing specification used in transmitting digital signals over a single 64 Kbps channel over a T1 facility. DS-3 is the framing specification used for transmitting digital signals at 44.736 Mbps on a T3 facility. DS-2 is not a defined framing specification.
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
114).

Physical
layer The Physical layer is responsible for the transmission of the data through the physical medium. This includes such things as cables. Fiber optics is a cabling mechanism which works at Physical layer of OSI model
All of the other answers are incorrect.
The following reference(s) were/was used to create this question: Shon Harris all in one - Chapter 7 (Cabling)

The differential backup method only copies files that have changed since the last full backup was performed. It is additive in the fact that it does not reset the archive bit so all changed or added files are backed up in every differential backup until the next full backup. The "additive backup method" is not a common backup method. 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 69).