Final answer:
The security control focused on preventing collusion is Separation of duties. This measure distributes responsibilities among multiple individuals, making fraudulent cooperation more challenging and detectable.
Step-by-step explanation:
The security control directly focused on preventing collusion is C. Separation of duties. Collusion is a scenario where two or more individuals work together to circumvent security measures, and the separation of duties is designed to prevent such cooperation by distributing responsibilities and privileges for a particular process among multiple people or job roles. This way, it requires the combined effort of several individuals to commit a fraudulent act, which is less likely and easier to detect.
The principle of least privilege, while a valuable security control, primarily limits access rights for users to the bare minimum necessary to perform their work. Qualitative risk analysis is a process that assesses the probability and impact of risks but does not directly prevent collusion. Finally, job descriptions outline a person's responsibilities but do not inherently include mechanisms to prevent collusion unless they specifically incorporate the aspect of separating duties as part of the role's design.