A corrective control is a control that aims to restore normal operations after a disruption or incident has occurred. Executing emergency response plans is an example of a corrective control, as it helps to mitigate the impact of an incident and resume business functions. Separating equipment development testing and production is a preventive control, as it helps to avoid errors or unauthorized changes in production systems.
Verifying duplicate calculations in data processing is a detective control, as it helps to identify errors or anomalies in data processing. Reviewing user access rights for segregation is also a detective control, as it helps to detect any violations of segregation of duties principles. References: ISACA, CISA Review Manual,
27th Edition, 2018, page 64

The activity most likely to increase internal audit quality is increasing audit staff training. ISACA's resources on audit capability and internal audit development consistently emphasize building knowledge and skills as a way to improve audit effectiveness and quality. Training strengthens auditors' technical competence, professional judgment, and ability to identify emerging and atypical risks.
Option A is correct because better-trained auditors are more capable of planning effectively, gathering reliable evidence, assessing controls, and producing useful findings. ISACA training resources emphasize foundational and practical audit knowledge, while reskilling guidance highlights the need for internal audit to improve capability in response to changing risks.
Option B is not the best answer because outsourcing may or may not improve quality; it depends on the provider and governance over the arrangement. It is not inherently more effective than developing internal capability.
Option C is incorrect because increasing the number of planned audits can easily reduce quality if resources are stretched thinner. More volume does not automatically mean better audit work.
Option D can support continuous improvement, but client surveys are an indirect feedback tool. They do not improve technical audit quality as directly as stronger auditor training and competency.
Therefore, A is the best answer because improving auditor competence through training is the most direct and reliable way to increase internal audit quality.
References (Official ISACA):
* ISACA, IT Audit Fundamentals Certificate - emphasizes foundational audit concepts and practical application of audit principles.
* ISACA Journal, Reskilling Internal Audit - highlights the need for internal audit to improve capabilities to identify emerging and atypical risk.
* ISACA Now Blog, Internal Auditing With an Agile Scrum Approach - collaboration and feedback can improve quality and relevance, but competence remains foundational.

The evidence collected during a digital forensic investigation would not be admissible in court if the logs failed to identify the person handling the evidence. This would violate the chain of custody principle, which requires that the evidence be properly documented, secured, and tracked throughout the investigation process.
The chain of custody ensures that the evidence is authentic, reliable, and trustworthy, and that it has not been tampered with or altered. The person who collected the evidence, whether qualified or not, is not relevant to the admissibility of the evidence, as long as they followed the proper procedures and protocols. The evidence collected by the internal forensics team can be admissible in court, as long as they are independent, objective, and competent. The evidence does not need to be fully backed up using a cloud-based solution prior to the trial, as long as it is preserved and protected from damage or loss. References: ISACA Journal Article: Digital Forensics: Chain of Custody

A heuristic intrusion detection system (IDS) provides the most protection against emerging threats, as it uses behavioral analysis and anomaly detection to identify unknown or zero-day attacks. A heuristic IDS can adapt to changing patterns and learn from previous incidents, making it more effective than a signature-based IDS, which relies on predefined rules and signatures to detect known attacks. A demilitarized zone (DMZ) is a network segment that separates the internal network from the external network, and it can provide some protection against external threats, but not against internal or emerging threats. Real-time updating of antivirus software is important to protect against malware, but it may not be sufficient to prevent new or sophisticated attacks that exploit unknown vulnerabilities. References: CISA Review Manual (Digital Version) 1, page 452-453.