The greatest impact as a result of the ongoing deterioration of a detective control is an increased number of false negatives in security logs. A detective control is a control that monitors and identifies any deviations or anomalies from the expected or normal behavior or performance of a system or process. A security log is a record of events or activities that occur within a system or network, such as user access, file changes, system errors, or security incidents. A false negative is a situation where a security log fails to detect or report an actual deviation or anomaly that has occurred, such as an unauthorized access, a malicious modification, or a security breach. An increased number of false negatives in security logs can have a significant impact on the organization's security posture and risk management, because it can prevent timely detection and response to security threats, compromise the accuracy and reliability of security monitoring and reporting, and undermine the accountability and auditability of user actions and transactions. The other options are not as impactful as an increased number of false negatives in security logs, because they either do not affect the detection capability of a detective control, or they have less severe consequences for security management. References:
CISA Review Manual (Digital Version)1, Chapter 5, Section 5.2.1

IT disaster recovery time objectives (RTOs) are the maximum acceptable time that an IT system can be unavailable after a disaster before it causes unacceptable consequences for the business. IT RTOs should be based on the business-defined criticality of the systems, which reflects how important they are for supporting the business processes and functions. The maximum tolerable loss of data, the nature of the outage, and the maximum tolerable downtime (MTD) are also factors that affect the IT RTOs, but they are not the primary basis for determining them.

A database administrator (DBA) is responsible for maintaining the integrity, security and performance of the database systems. A DBA who is also responsible for developing and executing changes into the production environment may have a conflict of interest and pose a risk to the data quality and availability. Therefore, the IS auditor should first identify whether any compensating controls exist to mitigate this risk, such as independent reviews, approvals, audits or monitoring of the changes. Determining whether another DBA could make the changes, reporting a potential segregation of duties violation and ensuring a change management process is followed prior to implementation are possible actions that the auditor could take after identifying the compensating controls or the lack thereof. References:
* : Database Administrator (DBA) Definition
* : Segregation of Duties | ISACA
* : [Compensating Control Definition]

Access authorization tables are the best way to achieve effective separation of duties in an online environment, as they allow the definition and enforcement of different access rights and privileges for different users or roles, based on the principle of least privilege12. Access authorization tables can help to prevent unauthorized or inappropriate actions, such as fraud, errors, or misuse of the system, by ensuring that no user has enough privileges to perform all parts of a transaction or business process34.
References
1: Separation of Duty (SOD) - Glossary | CSRC3 2: Separation of Duties within Information Systems4 3:
Separation of Duties: Implementation & Challenges in IT2 4: Implementing Segregation of Duties: A Practical Experience Based on Best Practices - ISACA1