Resilience is the ability of an organization to continue to operate effectively during or after a disruptive event. A business impact analysis (BIA) is a key process to identify the critical systems and processes that support the organization's objectives and determine the impact of their disruption. Without a BIA, the organization may not be able to prioritize the recovery of the most important systems and processes, which poses the greatest risk to its resilience. The other options are not as significant as a BIA, as they relate to data quality, system monitoring, and user acceptance testing, which are important but not essential for resilience. References: CISA Review Manual (Digital Version), Domain 4: Information Systems Operations and Business Resilience, Section 4.2 Business Continuity Planning1

Backup procedures for an organization's critical data are considered to be corrective controls, as they are designed to restore normal operations after a disruption or failure. Corrective controls aim to minimize the impact of an incident and prevent recurrence. Directive, detective and compensating controls are not related to backup procedures. Directive controls are intended to guide or instruct users to follow policies and procedures. Detective controls are intended to identify and report incidents or violations. Compensating controls are intended to mitigate the risk of a missing or ineffective primary control. References: CISA Review Manual (Digital Version), Chapter 2, Section 2.11

A preventive control is a control that aims to deter or prevent undesirable events from occurring. A fingerprint-based access control system for the building is an example of a preventive control for physical access, as it restricts unauthorized persons from entering the premises. Keeping log entries for all visitors to the building, installing CCTV cameras for all ingress and egress points, and implementing a centralized logging server to record instances of staff logging into workstations are examples of detective controls, which are controls that aim to discover or detect undesirable events that have already occurred.
References: IS Audit and Assurance Tools and Techniques, CISA Certification | Certified Information Systems Auditor | ISACA

The first step in auditing a data communication system is to determine the business use and types of messages to be transmitted. This is because the auditor needs to understand the purpose, scope, and objectives of the data communication system, as well as the nature, volume, and sensitivity of the data being transmitted. This will help the auditor to identify the risks, controls, and audit criteria for the data communication system.
Traffic volumes and response-time criteria, physical security for network equipment, and the level of redundancy in the various communication paths are important aspects of a data communication system, but they are not the first step in auditing it. They depend on the business use and types of messages to be transmitted, and they may vary according to different scenarios and requirements. References: CISA Review Manual (Digital Version), [ISACA Auditing Standards]