The greatest concern for an IS auditor when auditing an organization's IT strategy development process is that information security was not included as a key objective in the IT strategic plan. Information security is a vital component of IT strategy, as it ensures the confidentiality, integrity and availability of information assets, and supports the business objectives and regulatory compliance. The other options are not as significant as the lack of information security in the IT strategic plan. References: CISA Review Manual (Digital Version), Chapter 1, Section 1.31

In reviewing the IT strategic plan, the IS auditor should consider whether it identifies the major IT initiatives that are aligned with the organization's vision, mission, and objectives, and that support the business strategy and priorities12. The major IT initiatives should also be realistic, measurable, and achievable, and should have clear timelines, budgets, and responsibilities34.
References
1: IT Strategy Template for a Successful Strategic Plan | Gartner2 2: IT Strategy Template for a Successful Strategic Plan | Gartner4 3: Conduct a Strategic Plan Review & Assessment - Governance3 4: Time To Conduct A Strategy Review? Here's How To Get Started1

A service level agreement (SLA) is a contract between a service provider and a customer that defines the expected level of performance, risks, and capabilities of an IT infrastructure. An IS auditor can use an SLA to measure how well the IT infrastructure meets the business needs and objectives, as well as to identify any gaps or issues that need to be addressed. The other options are not directly related to measuring the performance, risks, and capabilities of an IT infrastructure. References:
* CISA Review Manual (Digital Version), Chapter 5, Section 5.2.11
* CISA Review Questions, Answers & Explanations Database, Question ID 203