An audit universe is a comprehensive list of all the auditable entities, processes, and activities within an organization. It helps the IS auditor to identify the scope, objectives, and priorities of the audit plan, as well as the resources and methodologies required to conduct the audits. An audit universe can also help the IS auditor to ensure that all the key risks, controls, and regulations are covered by the audit plan, and that there are no gaps or overlaps in the audit coverage.
The first activity that the IS auditor should perform when preparing a plan for audits to be carried out over a specified period is to determine the audit universe. This involves defining the criteria and methods for identifying and categorizing the auditable units, such as by business function, process, system, location, or risk level. The IS auditor should also consult with the management and otherstakeholders to obtain their input and expectations for the audit plan. The IS auditor should then document and validate the audit universe, and update it regularly to reflect any changes in the organization's structure, operations, or environment.
The other three activities are also important for preparing an audit plan, but they should be performed after determining the audit universe. Allocating audit resources involves assigning staff, time, budget, and tools to each audit based on their complexity, priority, and availability. Prioritizing risks involves assessing the likelihood and impact of each risk associated with each auditable unit, and ranking them according to their significance and urgency. Reviewing prior audit reports involves analyzing the findings, recommendations, and actions from previous audits related to each auditable unit, and evaluating their current status and relevance.
Therefore, determining the audit universe is the best answer.
References:
Audit Universe - UPDATED 2022 - Examples, Templates and More!
01 February 2023 Audit universe - IIA

The record-locking option of a database management system (DBMS) serves to eliminate the risk of concurrent updates to a record by different users or transactions. Record locking is a technique of preventing simultaneous access to data in a database, to prevent inconsistent results1. For example, if two bank clerks try to update the same bank account for two different transactions, record locking can ensure that only one clerk can modify the record at a time, while the other has to wait until the lock is released. This way, the record will reflect both transactions correctly and avoid data corruption.
Record locking does not serve to allow database administrators (DBAs) to record the activities of users. This is a function of auditing or logging, which can track the actions performed by users on the database2. Record locking does not affect the ability of DBAs to monitor or audit user activities.
Record locking does not serve to restrict users from changing certain values within records. This is a function of access control or authorization, which can enforce rules or policies on what data users can view or modify2. Record locking does not affect the permissions or privileges of users on the database.
Record locking does not serve to allow users to lock others out of their files. This is a function of encryption or password protection, which can secure files from unauthorized access or modification3. Record locking does not affect the security or confidentiality of files on the database.
References:
Record locking - Wikipedia1
Database security - Wikipedia2
File system permissions - Wikipedia3

The best criteria for monitoring an IT vendor's service levels are the performance metrics, as they provide quantifiable and measurable indicators of how well the vendor is delivering the agreed-upon services, such as availability, reliability, quality, timeliness, and customer satisfaction. A service auditor's report is a document that provides an independent opinion on the vendor's controls and processes, but it may not reflect the actual service levels or performance. A surprise visit to the vendor may help to verify the vendor's compliance and operations, but it may not be feasible or effective for monitoring the service levels on a regular basis. An interview with the vendor may help to obtain feedback and insights from the vendor's perspective, but it may not be objective or reliable formonitoring the service levels. References: CISA Review Manual(Digital Version), Chapter 2: Governanceand Management of IT, Section 2.4: IT Service Delivery and Support