In a controlled application development environment, the most important segregation of duties should be between the person who implements changes into the production environment and the application programmer. This segregation of duties ensures that no one person can create and deploy code without proper review, testing, and approval. This reduces the risk of errors, fraud, or malicious code being introduced into the production environment.
The other options are not as important as the segregation between the application programmer and the person who implements changes into production, but they are still relevant for achieving a secure and reliable application development environment. The segregation of duties between the person who implements changes into production and the systems programmer is important to prevent unauthorized or untested changes to system software or configuration. The segregation of duties between the person who implements changes into production and the computer operator is important to prevent unauthorized or uncontrolled access to production data or resources. The segregation of duties between the person who implements changes into production and the quality assurance (QA) personnel is important to ensure independent verification and validation of code quality and functionality.
References:
* ISACA CISA Review Manual 27th Edition (2019), page 247
* Segregation of Duties in an Agile Environment | AKF Partners3
* Separation of Duties: How to Conform in a DevOps World4

A business impact analysis (BIA) is a process that identifies and evaluates the potential effects of disruptions to critical business operations as a result of a disaster, accident or emergency. A BIA should include an inventory of relevant business processes that support the organization's strategic objectives and are essential for its continuity. The inventory should also identify the dependencies, interdependencies, recovery priorities and time frames for each business process. Policies for business procurement, documentation of application configurations and results of business resumption planning efforts are not as useful as an inventory of relevant business processes for performing a BIA. References:
* : Business Impact Analysis (BIA) Definition
* : Business Impact Analysis (BIA) | ISACA

Substantive testing provides the most reliable audit evidence on the validity of transactions in a financial application. Substantive testing is an audit procedure that examines the financial statements and supporting documentation to see if they contain errors or misstatements. Substantive testing can help to verify that the transactions recorded in the financial application are authorized, complete, accurate, and properly classified.
Substantive testing can include methods such as vouching, confirmation, analytical procedures, or physical examination.