PIR (Passive Infrared) detectors are most effective when motion occurs across the sensor's field of view. This maximizes the differential detection of body heat moving against the ambient background.
B and C (Movement toward/away) produce weaker thermal contrasts.
A (Defeat attempts) is a risk but not a mounting consideration.
References:
PSP Study Guide - Intrusion Detection Sensors
POA Manual - Motion Sensor Installation Guidelines

Conspiracy in the context of theft or fraud refers to two or more individuals collaborating-often using confusion or chaos in the environment-to execute or conceal a theft. This is especially common in employee- customer collusion or multi-person theft scenarios.
Accountability (B) reduces confusion.
Invoicing (C) is a documentation process.
Proliferation (D) means rapid increase, not relevant here.
References:
PSP Study Guide - Internal Threats and Collusion
ASIS POA Manual - Organizational Theft and Fraud

Site acceptance testing is the best choice because it verifies that the completed security system, once installed at the client's location, meets the physical and functional requirements stated in the contract. This form of testing confirms that the system performs properly in the actual operating environment, where real conditions such as layout, user interaction, workflows, and site-specific risks can affect performance. In organizational and Human Resource related operations, this is important because employees, supervisors, and security personnel must rely on systems that function correctly in daily practice, not only in theory or in a factory setting. Factory testing may confirm equipment quality before delivery, but it does not fully prove contract compliance after installation. Therefore, site acceptance testing provides the most reliable demonstration to the client that all specified requirements have been met.

The correct answer is C. environmental and degradation factors.
In PSP physical security design, lighting is treated as a structural security countermeasure, and the ASIS PSP Body of Knowledge includes knowledge of lighting, electronic security systems, performance requirements, and security system design capacities.
A 4:1 light-to-dark ratio means the brightest area should not be more than four times brighter than the darkest area within the assessed scene. This provides relatively even illumination for guards and video assessment systems. In physical protection system guidance, the light-to-dark ratio directly affects the ability to assess a scene; very high ratios create dark blind spots, while a lower ratio such as 4:1 greatly reduces those blind spots.
The reason 4:1 is used as the preferred design goal is that lighting systems degrade over time due to environmental and maintenance-related factors such as lamp aging, dirt on fixtures, weather effects, dust, damaged lamps, vegetation growth, and surface reflectance changes. Guidance on security camera lighting states that lighting may be designed for a 4-to-1 ratio to allow for degradation over time, while a 6-to-1 ratio is still used as a practical maximum to avoid areas becoming too dark or too bright for assessment.
The other options are not the best answer:
A). High surface reflection may help contrast, but it is not the reason for selecting a 4:1 design goal.
B). High aspect ratio is not a security lighting design objective in this context.
D). Reflected glare reduction is important, but the 4:1 ratio is mainly selected to maintain usable illumination despite environmental and degradation factors.
Therefore, the correct answer is C. environmental and degradation factors.