The impact if corrective actions are not taken is the most important factor to consider when scheduling follow- up audits. An IS auditor should prioritize the follow-up audits based on the risk and potential consequences of not addressing the audit findings and recommendations. The other options are less important factors that may affect the timing and scope of the follow-up audits, but not their necessity or urgency. References:
* CISA Review Manual(Digital Version), Chapter 2, Section 2.5.31
* CISA Review Questions, Answers & Explanations Database, Question ID 207

Control totals are a method of verifying the accuracy and completeness of data processing by comparing the totals of key fields in input and output records1. Control totals can be used to reduce the risk of incomplete processing, which is the failure to process all the data or transactions that are expected or required2.
Incomplete processing can result in data loss, inconsistency, or incompleteness, which can affect the quality and reliability of the information system and its outputs. Incomplete processing can be caused by various factors, such as:
Hardware or software failures that interrupt the processing or transmission of data2 Human errors or omissions that skip or miss some data or transactions2 Malicious attacks or unauthorized access that delete or modify some data or transactions2 Environmental hazards or disasters that damage or destroy some data or transactions2 Control totals can help detect and prevent incomplete processing by:
Providing a benchmark or reference point to compare the input and output data or transactions1 Identifying any discrepancies or deviations from the expected or required totals1 Alerting the users or operators to investigate and resolve the causes of incomplete processing1 Ensuring that all the data or transactions are properly transmitted, converted, and processed1 The other options are not as relevant as control totals for reducing the risk of incomplete processing. Posting to the wrong record is the error of assigning or transferring data or transactions to an incorrect account, file, or record3. Improper backup is the failure to create, store, or restore copies of data or transactions in case of loss, corruption, or damage4. Improper authorization is the lack of proper permission or approval to access, modify, or process data or transactions. Control totals may not be able to prevent or detect these errors or failures, as they are not related to the completeness of data processing. Therefore, option B is the correct answer.
References:
control totals - Barrons Dictionary - AllBusiness.com
What is control total amount? - Sage Advice US
Posting Error Definition
Backup Definition
[Authorization Definition]

A transaction processing system (TPS) is a system that captures, processes, and stores data related to business transactions1. A general ledger is a system that records the financial transactions of an organization in different accounts2. An interface is a connection point between two systems that allows data exchange3. A system fix is a change or update to a system that resolves a problem or improves its functionality4.
The IS auditor should recommend to perform periodic reconciliations to validate the interface between the TPS and the general ledger is working in the future. A reconciliation is a process of comparing and verifying the data in two systems to ensure accuracy and consistency1. By performing periodic reconciliations, the IS auditor can detect and correct any errors or discrepancies in the data, such as duplicate transactions, missing transactions, or incorrect amounts. This way, the IS auditor can ensure the reliability and integrity of the financial data in both systems.
The other options are not as effective as periodic reconciliations to validate the interface. System owner sign- off for the system fix is a form of approval that indicates the system owner agrees with the change and its expected outcome4. However, this does not guarantee that the system fix will work as intended or prevent future errors. Conducting functional testing is a process of verifying that the system performs its intended functions correctly and meets its requirements4. However, this is usually done before or after the system fix is implemented, not on an ongoing basis. Improving user acceptance testing (UAT) is a process of evaluating whether the system meets the needs and expectations of the end users4. However, this is also done before or after the system fix is implemented, not on an ongoing basis. Therefore, option A is the correct answer.
References:
Transaction Interface: Organization, Process, and System
Validation of Interfaces - Ensuring Data Integrity and Quality across Systems Oracle Payments Implementation Guide Receiving Transactions Inserted Into Interface Table as BATCH And PENDING Are Not Processed By Receiving Transaction Processor What Is a Transaction Processing System (TPS)? (Plus Types)